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 // Copyright (c) 2017-2020, University of Cincinnati, developed by Henry Schreiner
 // under NSF AWARD 1414736 and by the respective contributors.
 // All rights reserved.
 //
 // SPDX-License-Identifier: BSD-3-Clause
 
 #pragma once
 
 // [CLI11:public_includes:set]
 #include <algorithm>
 #include <cstdint>
 #include <functional>
 #include <iostream>
 #include <iterator>
 #include <memory>
 #include <numeric>
 #include <set>
 #include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
 // [CLI11:public_includes:end]
 
 // CLI Library includes
 #include "ConfigFwd.hpp"
 #include "Error.hpp"
 #include "FormatterFwd.hpp"
 #include "Macros.hpp"
 #include "Option.hpp"
 #include "Split.hpp"
 #include "StringTools.hpp"
 #include "TypeTools.hpp"
 
 namespace CLI {
 // [CLI11:app_hpp:verbatim]
 
 #ifndef CLI11_PARSE
 #define CLI11_PARSE(app, argc, argv)                                                                                   \
     try {                                                                                                              \
         (app).parse((argc), (argv));                                                                                   \
     } catch(const CLI::ParseError &e) {                                                                                \
         return (app).exit(e);                                                                                          \
     }
 #endif
 
 namespace detail {
 enum class Classifier { NONE, POSITIONAL_MARK, SHORT, LONG, WINDOWS_STYLE, SUBCOMMAND, SUBCOMMAND_TERMINATOR };
 struct AppFriend;
 }  // namespace detail
 
 namespace FailureMessage {
 std::string simple(const App *app, const Error &e);
 std::string help(const App *app, const Error &e);
 }  // namespace FailureMessage
 
 /// enumeration of modes of how to deal with extras in config files
 
 enum class config_extras_mode : char { error = 0, ignore, capture };
 
 class App;
 
 using App_p = std::shared_ptr<App>;
 
 class Option_group;
 /// Creates a command line program, with very few defaults.
 /** To use, create a new `Program()` instance with `argc`, `argv`, and a help description. The templated
  *  add_option methods make it easy to prepare options. Remember to call `.start` before starting your
  * program, so that the options can be evaluated and the help option doesn't accidentally run your program. */
 class App {
     friend Option;
     friend detail::AppFriend;
 
   protected:
     // This library follows the Google style guide for member names ending in underscores
 
     /// @name Basics
     ///@{
 
     /// Subcommand name or program name (from parser if name is empty)
     std::string name_{};
 
     /// Description of the current program/subcommand
     std::string description_{};
 
     /// If true, allow extra arguments (ie, don't throw an error). INHERITABLE
     bool allow_extras_{false};
 
     /// If ignore, allow extra arguments in the ini file (ie, don't throw an error). INHERITABLE
     /// if error error on an extra argument, and if capture feed it to the app
     config_extras_mode allow_config_extras_{config_extras_mode::ignore};
 
     ///  If true, return immediately on an unrecognized option (implies allow_extras) INHERITABLE
     bool prefix_command_{false};
 
     /// If set to true the name was automatically generated from the command line vs a user set name
     bool has_automatic_name_{false};
 
     /// If set to true the subcommand is required to be processed and used, ignored for main app
     bool required_{false};
 
     /// If set to true the subcommand is disabled and cannot be used, ignored for main app
     bool disabled_{false};
 
     /// Flag indicating that the pre_parse_callback has been triggered
     bool pre_parse_called_{false};
 
     /// Flag indicating that the callback for the subcommand should be executed immediately on parse completion which is
     /// before help or ini files are processed. INHERITABLE
     bool immediate_callback_{false};
 
     /// This is a function that runs prior to the start of parsing
     std::function<void(std::size_t)> pre_parse_callback_{};
 
     /// This is a function that runs when parsing has finished.
     std::function<void()> parse_complete_callback_{};
 
     /// This is a function that runs when all processing has completed
     std::function<void()> final_callback_{};
 
     ///@}
     /// @name Options
     ///@{
 
     /// The default values for options, customizable and changeable INHERITABLE
     OptionDefaults option_defaults_{};
 
     /// The list of options, stored locally
     std::vector<Option_p> options_{};
 
     ///@}
     /// @name Help
     ///@{
 
     /// Footer to put after all options in the help output INHERITABLE
     std::string footer_{};
 
     /// This is a function that generates a footer to put after all other options in help output
     std::function<std::string()> footer_callback_{};
 
     /// A pointer to the help flag if there is one INHERITABLE
     Option *help_ptr_{nullptr};
 
     /// A pointer to the help all flag if there is one INHERITABLE
     Option *help_all_ptr_{nullptr};
 
     /// A pointer to a version flag if there is one
     Option *version_ptr_{nullptr};
 
     /// This is the formatter for help printing. Default provided. INHERITABLE (same pointer)
     std::shared_ptr<FormatterBase> formatter_{new Formatter()};
 
     /// The error message printing function INHERITABLE
     std::function<std::string(const App *, const Error &e)> failure_message_{FailureMessage::simple};
 
     ///@}
     /// @name Parsing
     ///@{
 
     using missing_t = std::vector<std::pair<detail::Classifier, std::string>>;
 
     /// Pair of classifier, string for missing options. (extra detail is removed on returning from parse)
     ///
     /// This is faster and cleaner than storing just a list of strings and reparsing. This may contain the -- separator.
     missing_t missing_{};
 
     /// This is a list of pointers to options with the original parse order
     std::vector<Option *> parse_order_{};
 
     /// This is a list of the subcommands collected, in order
     std::vector<App *> parsed_subcommands_{};
 
     /// this is a list of subcommands that are exclusionary to this one
     std::set<App *> exclude_subcommands_{};
 
     /// This is a list of options which are exclusionary to this App, if the options were used this subcommand should
     /// not be
     std::set<Option *> exclude_options_{};
 
     /// this is a list of subcommands or option groups that are required by this one, the list is not mutual,  the
     /// listed subcommands do not require this one
     std::set<App *> need_subcommands_{};
 
     /// This is a list of options which are required by this app, the list is not mutual, listed options do not need the
     /// subcommand not be
     std::set<Option *> need_options_{};
 
     ///@}
     /// @name Subcommands
     ///@{
 
     /// Storage for subcommand list
     std::vector<App_p> subcommands_{};
 
     /// If true, the program name is not case sensitive INHERITABLE
     bool ignore_case_{false};
 
     /// If true, the program should ignore underscores INHERITABLE
     bool ignore_underscore_{false};
 
     /// Allow subcommand fallthrough, so that parent commands can collect commands after subcommand.  INHERITABLE
     bool fallthrough_{false};
 
     /// Allow '/' for options for Windows like options. Defaults to true on Windows, false otherwise. INHERITABLE
     bool allow_windows_style_options_{
 #ifdef _WIN32
         true
 #else
         false
 #endif
     };
     /// specify that positional arguments come at the end of the argument sequence not inheritable
     bool positionals_at_end_{false};
 
     enum class startup_mode : char { stable, enabled, disabled };
     /// specify the startup mode for the app
     /// stable=no change, enabled= startup enabled, disabled=startup disabled
     startup_mode default_startup{startup_mode::stable};
 
     /// if set to true the subcommand can be triggered via configuration files INHERITABLE
     bool configurable_{false};
 
     /// If set to true positional options are validated before assigning INHERITABLE
     bool validate_positionals_{false};
 
     /// indicator that the subcommand is silent and won't show up in subcommands list
     /// This is potentially useful as a modifier subcommand
     bool silent_{false};
 
     /// Counts the number of times this command/subcommand was parsed
     std::uint32_t parsed_{0U};
 
     /// Minimum required subcommands (not inheritable!)
     std::size_t require_subcommand_min_{0};
 
     /// Max number of subcommands allowed (parsing stops after this number). 0 is unlimited INHERITABLE
     std::size_t require_subcommand_max_{0};
 
     /// Minimum required options (not inheritable!)
     std::size_t require_option_min_{0};
 
     /// Max number of options allowed. 0 is unlimited (not inheritable)
     std::size_t require_option_max_{0};
 
     /// A pointer to the parent if this is a subcommand
     App *parent_{nullptr};
 
     /// The group membership INHERITABLE
     std::string group_{"Subcommands"};
 
     /// Alias names for the subcommand
     std::vector<std::string> aliases_{};
 
     ///@}
     /// @name Config
     ///@{
 
     /// Pointer to the config option
     Option *config_ptr_{nullptr};
 
     /// This is the formatter for help printing. Default provided. INHERITABLE (same pointer)
     std::shared_ptr<Config> config_formatter_{new ConfigTOML()};
 
     ///@}
 
     /// Special private constructor for subcommand
     App(std::string app_description, std::string app_name, App *parent)
         : name_(std::move(app_name)), description_(std::move(app_description)), parent_(parent) {
         // Inherit if not from a nullptr
         if(parent_ != nullptr) {
             if(parent_->help_ptr_ != nullptr)
                 set_help_flag(parent_->help_ptr_->get_name(false, true), parent_->help_ptr_->get_description());
             if(parent_->help_all_ptr_ != nullptr)
                 set_help_all_flag(parent_->help_all_ptr_->get_name(false, true),
                                   parent_->help_all_ptr_->get_description());
 
             /// OptionDefaults
             option_defaults_ = parent_->option_defaults_;
 
             // INHERITABLE
             failure_message_ = parent_->failure_message_;
             allow_extras_ = parent_->allow_extras_;
             allow_config_extras_ = parent_->allow_config_extras_;
             prefix_command_ = parent_->prefix_command_;
             immediate_callback_ = parent_->immediate_callback_;
             ignore_case_ = parent_->ignore_case_;
             ignore_underscore_ = parent_->ignore_underscore_;
             fallthrough_ = parent_->fallthrough_;
             validate_positionals_ = parent_->validate_positionals_;
             configurable_ = parent_->configurable_;
             allow_windows_style_options_ = parent_->allow_windows_style_options_;
             group_ = parent_->group_;
             footer_ = parent_->footer_;
             formatter_ = parent_->formatter_;
             config_formatter_ = parent_->config_formatter_;
             require_subcommand_max_ = parent_->require_subcommand_max_;
         }
     }
 
   public:
     /// @name Basic
     ///@{
 
     /// Create a new program. Pass in the same arguments as main(), along with a help string.
     explicit App(std::string app_description = "", std::string app_name = "")
         : App(app_description, app_name, nullptr) {
         set_help_flag("-h,--help", "Print this help message and exit");
     }
 
     App(const App &) = delete;
     App &operator=(const App &) = delete;
 
     /// virtual destructor
     virtual ~App() = default;
 
     /// Set a callback for execution when all parsing and processing has completed
     ///
     /// Due to a bug in c++11,
     /// it is not possible to overload on std::function (fixed in c++14
     /// and backported to c++11 on newer compilers). Use capture by reference
     /// to get a pointer to App if needed.
     App *callback(std::function<void()> app_callback) {
         if(immediate_callback_) {
             parse_complete_callback_ = std::move(app_callback);
         } else {
             final_callback_ = std::move(app_callback);
         }
         return this;
     }
 
     /// Set a callback for execution when all parsing and processing has completed
     /// aliased as callback
     App *final_callback(std::function<void()> app_callback) {
         final_callback_ = std::move(app_callback);
         return this;
     }
 
     /// Set a callback to execute when parsing has completed for the app
     ///
     App *parse_complete_callback(std::function<void()> pc_callback) {
         parse_complete_callback_ = std::move(pc_callback);
         return this;
     }
 
     /// Set a callback to execute prior to parsing.
     ///
     App *preparse_callback(std::function<void(std::size_t)> pp_callback) {
         pre_parse_callback_ = std::move(pp_callback);
         return this;
     }
 
     /// Set a name for the app (empty will use parser to set the name)
     App *name(std::string app_name = "") {
 
         if(parent_ != nullptr) {
             auto oname = name_;
             name_ = app_name;
             auto &res = _compare_subcommand_names(*this, *_get_fallthrough_parent());
             if(!res.empty()) {
                 name_ = oname;
                 throw(OptionAlreadyAdded(app_name + " conflicts with existing subcommand names"));
             }
         } else {
             name_ = app_name;
         }
         has_automatic_name_ = false;
         return this;
     }
 
     /// Set an alias for the app
     App *alias(std::string app_name) {
         if(!detail::valid_name_string(app_name)) {
             if(app_name.empty()) {
                 throw IncorrectConstruction("Empty aliases are not allowed");
             }
             if(!detail::valid_first_char(app_name[0])) {
                 throw IncorrectConstruction(
                     "Alias starts with invalid character, allowed characters are [a-zA-z0-9]+'_','?','@' ");
             }
             for(auto c : app_name) {
                 if(!detail::valid_later_char(c)) {
                     throw IncorrectConstruction(std::string("Alias contains invalid character ('") + c +
                                                 "'), allowed characters are "
                                                 "[a-zA-z0-9]+'_','?','@','.','-' ");
                 }
             }
         }
 
         if(parent_ != nullptr) {
             aliases_.push_back(app_name);
             auto &res = _compare_subcommand_names(*this, *_get_fallthrough_parent());
             if(!res.empty()) {
                 aliases_.pop_back();
                 throw(OptionAlreadyAdded("alias already matches an existing subcommand: " + app_name));
             }
         } else {
             aliases_.push_back(app_name);
         }
 
         return this;
     }
 
     /// Remove the error when extras are left over on the command line.
     App *allow_extras(bool allow = true) {
         allow_extras_ = allow;
         return this;
     }
 
     /// Remove the error when extras are left over on the command line.
     App *required(bool require = true) {
         required_ = require;
         return this;
     }
 
     /// Disable the subcommand or option group
     App *disabled(bool disable = true) {
         disabled_ = disable;
         return this;
     }
 
     /// silence the subcommand from showing up in the processed list
     App *silent(bool silence = true) {
         silent_ = silence;
         return this;
     }
 
     /// Set the subcommand to be disabled by default, so on clear(), at the start of each parse it is disabled
     App *disabled_by_default(bool disable = true) {
         if(disable) {
             default_startup = startup_mode::disabled;
         } else {
             default_startup = (default_startup == startup_mode::enabled) ? startup_mode::enabled : startup_mode::stable;
         }
         return this;
     }
 
     /// Set the subcommand to be enabled by default, so on clear(), at the start of each parse it is enabled (not
     /// disabled)
     App *enabled_by_default(bool enable = true) {
         if(enable) {
             default_startup = startup_mode::enabled;
         } else {
             default_startup =
                 (default_startup == startup_mode::disabled) ? startup_mode::disabled : startup_mode::stable;
         }
         return this;
     }
 
     /// Set the subcommand callback to be executed immediately on subcommand completion
     App *immediate_callback(bool immediate = true) {
         immediate_callback_ = immediate;
         if(immediate_callback_) {
             if(final_callback_ && !(parse_complete_callback_)) {
                 std::swap(final_callback_, parse_complete_callback_);
             }
         } else if(!(final_callback_) && parse_complete_callback_) {
             std::swap(final_callback_, parse_complete_callback_);
         }
         return this;
     }
 
     /// Set the subcommand to validate positional arguments before assigning
     App *validate_positionals(bool validate = true) {
         validate_positionals_ = validate;
         return this;
     }
 
     /// ignore extras in config files
     App *allow_config_extras(bool allow = true) {
         if(allow) {
             allow_config_extras_ = config_extras_mode::capture;
             allow_extras_ = true;
         } else {
             allow_config_extras_ = config_extras_mode::error;
         }
         return this;
     }
 
     /// ignore extras in config files
     App *allow_config_extras(config_extras_mode mode) {
         allow_config_extras_ = mode;
         return this;
     }
 
     /// Do not parse anything after the first unrecognized option and return
     App *prefix_command(bool allow = true) {
         prefix_command_ = allow;
         return this;
     }
 
     /// Ignore case. Subcommands inherit value.
     App *ignore_case(bool value = true) {
         if(value && !ignore_case_) {
             ignore_case_ = true;
             auto *p = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
             auto &match = _compare_subcommand_names(*this, *p);
             if(!match.empty()) {
                 ignore_case_ = false;  // we are throwing so need to be exception invariant
                 throw OptionAlreadyAdded("ignore case would cause subcommand name conflicts: " + match);
             }
         }
         ignore_case_ = value;
         return this;
     }
 
     /// Allow windows style options, such as `/opt`. First matching short or long name used. Subcommands inherit
     /// value.
     App *allow_windows_style_options(bool value = true) {
         allow_windows_style_options_ = value;
         return this;
     }
 
     /// Specify that the positional arguments are only at the end of the sequence
     App *positionals_at_end(bool value = true) {
         positionals_at_end_ = value;
         return this;
     }
 
     /// Specify that the subcommand can be triggered by a config file
     App *configurable(bool value = true) {
         configurable_ = value;
         return this;
     }
 
     /// Ignore underscore. Subcommands inherit value.
     App *ignore_underscore(bool value = true) {
         if(value && !ignore_underscore_) {
             ignore_underscore_ = true;
             auto *p = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
             auto &match = _compare_subcommand_names(*this, *p);
             if(!match.empty()) {
                 ignore_underscore_ = false;
                 throw OptionAlreadyAdded("ignore underscore would cause subcommand name conflicts: " + match);
             }
         }
         ignore_underscore_ = value;
         return this;
     }
 
     /// Set the help formatter
     App *formatter(std::shared_ptr<FormatterBase> fmt) {
         formatter_ = fmt;
         return this;
     }
 
     /// Set the help formatter
     App *formatter_fn(std::function<std::string(const App *, std::string, AppFormatMode)> fmt) {
         formatter_ = std::make_shared<FormatterLambda>(fmt);
         return this;
     }
 
     /// Set the config formatter
     App *config_formatter(std::shared_ptr<Config> fmt) {
         config_formatter_ = fmt;
         return this;
     }
 
     /// Check to see if this subcommand was parsed, true only if received on command line.
     bool parsed() const { return parsed_ > 0; }
 
     /// Get the OptionDefault object, to set option defaults
     OptionDefaults *option_defaults() { return &option_defaults_; }
 
     ///@}
     /// @name Adding options
     ///@{
 
     /// Add an option, will automatically understand the type for common types.
     ///
     /// To use, create a variable with the expected type, and pass it in after the name.
     /// After start is called, you can use count to see if the value was passed, and
     /// the value will be initialized properly. Numbers, vectors, and strings are supported.
     ///
     /// ->required(), ->default, and the validators are options,
     /// The positional options take an optional number of arguments.
     ///
     /// For example,
     ///
     ///     std::string filename;
     ///     program.add_option("filename", filename, "description of filename");
     ///
     Option *add_option(std::string option_name,
                        callback_t option_callback,
                        std::string option_description = "",
                        bool defaulted = false,
                        std::function<std::string()> func = {}) {
         Option myopt{option_name, option_description, option_callback, this};
 
         if(std::find_if(std::begin(options_), std::end(options_), [&myopt](const Option_p &v) {
                return *v == myopt;
            }) == std::end(options_)) {
             options_.emplace_back();
             Option_p &option = options_.back();
             option.reset(new Option(option_name, option_description, option_callback, this));
 
             // Set the default string capture function
             option->default_function(func);
 
             // For compatibility with CLI11 1.7 and before, capture the default string here
             if(defaulted)
                 option->capture_default_str();
 
             // Transfer defaults to the new option
             option_defaults_.copy_to(option.get());
 
             // Don't bother to capture if we already did
             if(!defaulted && option->get_always_capture_default())
                 option->capture_default_str();
 
             return option.get();
         }
         // we know something matches now find what it is so we can produce more error information
         for(auto &opt : options_) {
             auto &matchname = opt->matching_name(myopt);
             if(!matchname.empty()) {
                 throw(OptionAlreadyAdded("added option matched existing option name: " + matchname));
             }
         }
         // this line should not be reached the above loop should trigger the throw
         throw(OptionAlreadyAdded("added option matched existing option name"));  // LCOV_EXCL_LINE
     }
 
     /// Add option for assigning to a variable
     template <typename AssignTo,
               typename ConvertTo = AssignTo,
               enable_if_t<!std::is_const<ConvertTo>::value, detail::enabler> = detail::dummy>
     Option *add_option(std::string option_name,
                        AssignTo &variable,  ///< The variable to set
                        std::string option_description = "") {
 
         auto fun = [&variable](const CLI::results_t &res) {  // comment for spacing
             return detail::lexical_conversion<AssignTo, ConvertTo>(res, variable);
         };
 
         Option *opt = add_option(option_name, fun, option_description, false, [&variable]() {
             return CLI::detail::checked_to_string<AssignTo, ConvertTo>(variable);
         });
         opt->type_name(detail::type_name<ConvertTo>());
         // these must be actual lvalues since (std::max) sometimes is defined in terms of references and references
         // to structs used in the evaluation can be temporary so that would cause issues.
         auto Tcount = detail::type_count<AssignTo>::value;
         auto XCcount = detail::type_count<ConvertTo>::value;
         opt->type_size(detail::type_count_min<ConvertTo>::value, (std::max)(Tcount, XCcount));
         opt->expected(detail::expected_count<ConvertTo>::value);
         opt->run_callback_for_default();
         return opt;
     }
 
     /// Add option for assigning to a variable
     template <typename AssignTo, enable_if_t<!std::is_const<AssignTo>::value, detail::enabler> = detail::dummy>
     Option *add_option_no_stream(std::string option_name,
                                  AssignTo &variable,  ///< The variable to set
                                  std::string option_description = "") {
 
         auto fun = [&variable](const CLI::results_t &res) {  // comment for spacing
             return detail::lexical_conversion<AssignTo, AssignTo>(res, variable);
         };
 
         Option *opt = add_option(option_name, fun, option_description, false, []() { return std::string{}; });
         opt->type_name(detail::type_name<AssignTo>());
         opt->type_size(detail::type_count_min<AssignTo>::value, detail::type_count<AssignTo>::value);
         opt->expected(detail::expected_count<AssignTo>::value);
         opt->run_callback_for_default();
         return opt;
     }
 
     /// Add option for a callback of a specific type
     template <typename ArgType>
     Option *add_option_function(std::string option_name,
                                 const std::function<void(const ArgType &)> &func,  ///< the callback to execute
                                 std::string option_description = "") {
 
         auto fun = [func](const CLI::results_t &res) {
             ArgType variable;
             bool result = detail::lexical_conversion<ArgType, ArgType>(res, variable);
             if(result) {
                 func(variable);
             }
             return result;
         };
 
         Option *opt = add_option(option_name, std::move(fun), option_description, false);
         opt->type_name(detail::type_name<ArgType>());
         opt->type_size(detail::type_count_min<ArgType>::value, detail::type_count<ArgType>::value);
         opt->expected(detail::expected_count<ArgType>::value);
         return opt;
     }
 
     /// Add option with no description or variable assignment
     Option *add_option(std::string option_name) {
         return add_option(option_name, CLI::callback_t{}, std::string{}, false);
     }
 
     /// Add option with description but with no variable assignment or callback
     template <typename T,
               enable_if_t<std::is_const<T>::value && std::is_constructible<std::string, T>::value, detail::enabler> =
                   detail::dummy>
     Option *add_option(std::string option_name, T &option_description) {
         return add_option(option_name, CLI::callback_t(), option_description, false);
     }
 
     /// Set a help flag, replace the existing one if present
     Option *set_help_flag(std::string flag_name = "", const std::string &help_description = "") {
         // take flag_description by const reference otherwise add_flag tries to assign to help_description
         if(help_ptr_ != nullptr) {
             remove_option(help_ptr_);
             help_ptr_ = nullptr;
         }
 
         // Empty name will simply remove the help flag
         if(!flag_name.empty()) {
             help_ptr_ = add_flag(flag_name, help_description);
             help_ptr_->configurable(false);
         }
 
         return help_ptr_;
     }
 
     /// Set a help all flag, replaced the existing one if present
     Option *set_help_all_flag(std::string help_name = "", const std::string &help_description = "") {
         // take flag_description by const reference otherwise add_flag tries to assign to flag_description
         if(help_all_ptr_ != nullptr) {
             remove_option(help_all_ptr_);
             help_all_ptr_ = nullptr;
         }
 
         // Empty name will simply remove the help all flag
         if(!help_name.empty()) {
             help_all_ptr_ = add_flag(help_name, help_description);
             help_all_ptr_->configurable(false);
         }
 
         return help_all_ptr_;
     }
 
     /// Set a version flag and version display string, replace the existing one if present
     Option *set_version_flag(std::string flag_name = "",
                              const std::string &versionString = "",
                              const std::string &version_help = "Display program version information and exit") {
         // take flag_description by const reference otherwise add_flag tries to assign to version_description
         if(version_ptr_ != nullptr) {
             remove_option(version_ptr_);
             version_ptr_ = nullptr;
         }
 
         // Empty name will simply remove the version flag
         if(!flag_name.empty()) {
             version_ptr_ = add_flag_callback(
                 flag_name, [versionString]() { throw(CLI::CallForVersion(versionString, 0)); }, version_help);
             version_ptr_->configurable(false);
         }
 
         return version_ptr_;
     }
     /// Generate the version string through a callback function
     Option *set_version_flag(std::string flag_name,
                              std::function<std::string()> vfunc,
                              const std::string &version_help = "Display program version information and exit") {
         if(version_ptr_ != nullptr) {
             remove_option(version_ptr_);
             version_ptr_ = nullptr;
         }
 
         // Empty name will simply remove the version flag
         if(!flag_name.empty()) {
             version_ptr_ = add_flag_callback(
                 flag_name, [vfunc]() { throw(CLI::CallForVersion(vfunc(), 0)); }, version_help);
             version_ptr_->configurable(false);
         }
 
         return version_ptr_;
     }
 
   private:
     /// Internal function for adding a flag
     Option *_add_flag_internal(std::string flag_name, CLI::callback_t fun, std::string flag_description) {
         Option *opt;
         if(detail::has_default_flag_values(flag_name)) {
             // check for default values and if it has them
             auto flag_defaults = detail::get_default_flag_values(flag_name);
             detail::remove_default_flag_values(flag_name);
             opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
             for(const auto &fname : flag_defaults)
                 opt->fnames_.push_back(fname.first);
             opt->default_flag_values_ = std::move(flag_defaults);
         } else {
             opt = add_option(std::move(flag_name), std::move(fun), std::move(flag_description), false);
         }
         // flags cannot have positional values
         if(opt->get_positional()) {
             auto pos_name = opt->get_name(true);
             remove_option(opt);
             throw IncorrectConstruction::PositionalFlag(pos_name);
         }
         opt->multi_option_policy(MultiOptionPolicy::TakeLast);
         opt->expected(0);
         opt->required(false);
         return opt;
     }
 
   public:
     /// Add a flag with no description or variable assignment
     Option *add_flag(std::string flag_name) { return _add_flag_internal(flag_name, CLI::callback_t(), std::string{}); }
 
     /// Add flag with description but with no variable assignment or callback
     /// takes a constant string,  if a variable string is passed that variable will be assigned the results from the
     /// flag
     template <typename T,
               enable_if_t<std::is_const<T>::value && std::is_constructible<std::string, T>::value, detail::enabler> =
                   detail::dummy>
     Option *add_flag(std::string flag_name, T &flag_description) {
         return _add_flag_internal(flag_name, CLI::callback_t(), flag_description);
     }
 
     /// Add option for flag with integer result - defaults to allowing multiple passings, but can be forced to one
     /// if `multi_option_policy(CLI::MultiOptionPolicy::Throw)` is used.
     template <typename T,
               enable_if_t<std::is_constructible<T, std::int64_t>::value && !is_bool<T>::value, detail::enabler> =
                   detail::dummy>
     Option *add_flag(std::string flag_name,
                      T &flag_count,  ///< A variable holding the count
                      std::string flag_description = "") {
         flag_count = 0;
         CLI::callback_t fun = [&flag_count](const CLI::results_t &res) {
             try {
                 detail::sum_flag_vector(res, flag_count);
             } catch(const std::invalid_argument &) {
                 return false;
             }
             return true;
         };
         return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description))
             ->multi_option_policy(MultiOptionPolicy::TakeAll);
     }
 
     /// Other type version accepts all other types that are not vectors such as bool, enum, string or other classes
     /// that can be converted from a string
     template <typename T,
               enable_if_t<!detail::is_mutable_container<T>::value && !std::is_const<T>::value &&
                               (!std::is_constructible<T, std::int64_t>::value || is_bool<T>::value) &&
                               !std::is_constructible<std::function<void(int)>, T>::value,
                           detail::enabler> = detail::dummy>
     Option *add_flag(std::string flag_name,
                      T &flag_result,  ///< A variable holding true if passed
                      std::string flag_description = "") {
 
         CLI::callback_t fun = [&flag_result](const CLI::results_t &res) {
             return CLI::detail::lexical_cast(res[0], flag_result);
         };
         return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description))->run_callback_for_default();
     }
 
     /// Vector version to capture multiple flags.
     template <typename T,
               enable_if_t<!std::is_assignable<std::function<void(std::int64_t)> &, T>::value, detail::enabler> =
                   detail::dummy>
     Option *add_flag(std::string flag_name,
                      std::vector<T> &flag_results,  ///< A vector of values with the flag results
                      std::string flag_description = "") {
         CLI::callback_t fun = [&flag_results](const CLI::results_t &res) {
             bool retval = true;
             for(const auto &elem : res) {
                 flag_results.emplace_back();
                 retval &= detail::lexical_cast(elem, flag_results.back());
             }
             return retval;
         };
         return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description))
             ->multi_option_policy(MultiOptionPolicy::TakeAll)
             ->run_callback_for_default();
     }
 
     /// Add option for callback that is triggered with a true flag and takes no arguments
     Option *add_flag_callback(std::string flag_name,
                               std::function<void(void)> function,  ///< A function to call, void(void)
                               std::string flag_description = "") {
 
         CLI::callback_t fun = [function](const CLI::results_t &res) {
             bool trigger{false};
             auto result = CLI::detail::lexical_cast(res[0], trigger);
             if(result && trigger) {
                 function();
             }
             return result;
         };
         return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description));
     }
 
     /// Add option for callback with an integer value
     Option *add_flag_function(std::string flag_name,
                               std::function<void(std::int64_t)> function,  ///< A function to call, void(int)
                               std::string flag_description = "") {
 
         CLI::callback_t fun = [function](const CLI::results_t &res) {
             std::int64_t flag_count = 0;
             detail::sum_flag_vector(res, flag_count);
             function(flag_count);
             return true;
         };
         return _add_flag_internal(flag_name, std::move(fun), std::move(flag_description))
             ->multi_option_policy(MultiOptionPolicy::TakeAll);
     }
 
 #ifdef CLI11_CPP14
     /// Add option for callback (C++14 or better only)
     Option *add_flag(std::string flag_name,
                      std::function<void(std::int64_t)> function,  ///< A function to call, void(std::int64_t)
                      std::string flag_description = "") {
         return add_flag_function(std::move(flag_name), std::move(function), std::move(flag_description));
     }
 #endif
 
     /// Set a configuration ini file option, or clear it if no name passed
     Option *set_config(std::string option_name = "",
                        std::string default_filename = "",
                        const std::string &help_message = "Read an ini file",
                        bool config_required = false) {
 
         // Remove existing config if present
         if(config_ptr_ != nullptr) {
             remove_option(config_ptr_);
             config_ptr_ = nullptr;  // need to remove the config_ptr completely
         }
 
         // Only add config if option passed
         if(!option_name.empty()) {
             config_ptr_ = add_option(option_name, help_message);
             if(config_required) {
                 config_ptr_->required();
             }
             if(!default_filename.empty()) {
                 config_ptr_->default_str(std::move(default_filename));
             }
             config_ptr_->configurable(false);
         }
 
         return config_ptr_;
     }
 
     /// Removes an option from the App. Takes an option pointer. Returns true if found and removed.
     bool remove_option(Option *opt) {
         // Make sure no links exist
         for(Option_p &op : options_) {
             op->remove_needs(opt);
             op->remove_excludes(opt);
         }
 
         if(help_ptr_ == opt)
             help_ptr_ = nullptr;
         if(help_all_ptr_ == opt)
             help_all_ptr_ = nullptr;
 
         auto iterator =
             std::find_if(std::begin(options_), std::end(options_), [opt](const Option_p &v) { return v.get() == opt; });
         if(iterator != std::end(options_)) {
             options_.erase(iterator);
             return true;
         }
         return false;
     }
 
     /// creates an option group as part of the given app
     template <typename T = Option_group>
     T *add_option_group(std::string group_name, std::string group_description = "") {
         auto option_group = std::make_shared<T>(std::move(group_description), group_name, this);
         auto ptr = option_group.get();
         // move to App_p for overload resolution on older gcc versions
         App_p app_ptr = std::dynamic_pointer_cast<App>(option_group);
         add_subcommand(std::move(app_ptr));
         return ptr;
     }
 
     ///@}
     /// @name Subcommands
     ///@{
 
     /// Add a subcommand. Inherits INHERITABLE and OptionDefaults, and help flag
     App *add_subcommand(std::string subcommand_name = "", std::string subcommand_description = "") {
         if(!subcommand_name.empty() && !detail::valid_name_string(subcommand_name)) {
             if(!detail::valid_first_char(subcommand_name[0])) {
                 throw IncorrectConstruction(
                     "Subcommand name starts with invalid character, allowed characters are [a-zA-z0-9]+'_','?','@' ");
             }
             for(auto c : subcommand_name) {
                 if(!detail::valid_later_char(c)) {
                     throw IncorrectConstruction(std::string("Subcommand name contains invalid character ('") + c +
                                                 "'), allowed characters are "
                                                 "[a-zA-z0-9]+'_','?','@','.','-' ");
                 }
             }
         }
         CLI::App_p subcom = std::shared_ptr<App>(new App(std::move(subcommand_description), subcommand_name, this));
         return add_subcommand(std::move(subcom));
     }
 
     /// Add a previously created app as a subcommand
     App *add_subcommand(CLI::App_p subcom) {
         if(!subcom)
             throw IncorrectConstruction("passed App is not valid");
         auto ckapp = (name_.empty() && parent_ != nullptr) ? _get_fallthrough_parent() : this;
         auto &mstrg = _compare_subcommand_names(*subcom, *ckapp);
         if(!mstrg.empty()) {
             throw(OptionAlreadyAdded("subcommand name or alias matches existing subcommand: " + mstrg));
         }
         subcom->parent_ = this;
         subcommands_.push_back(std::move(subcom));
         return subcommands_.back().get();
     }
 
     /// Removes a subcommand from the App. Takes a subcommand pointer. Returns true if found and removed.
     bool remove_subcommand(App *subcom) {
         // Make sure no links exist
         for(App_p &sub : subcommands_) {
             sub->remove_excludes(subcom);
             sub->remove_needs(subcom);
         }
 
         auto iterator = std::find_if(
             std::begin(subcommands_), std::end(subcommands_), [subcom](const App_p &v) { return v.get() == subcom; });
         if(iterator != std::end(subcommands_)) {
             subcommands_.erase(iterator);
             return true;
         }
         return false;
     }
     /// Check to see if a subcommand is part of this command (doesn't have to be in command line)
     /// returns the first subcommand if passed a nullptr
     App *get_subcommand(const App *subcom) const {
         if(subcom == nullptr)
             throw OptionNotFound("nullptr passed");
         for(const App_p &subcomptr : subcommands_)
             if(subcomptr.get() == subcom)
                 return subcomptr.get();
         throw OptionNotFound(subcom->get_name());
     }
 
     /// Check to see if a subcommand is part of this command (text version)
     App *get_subcommand(std::string subcom) const {
         auto subc = _find_subcommand(subcom, false, false);
         if(subc == nullptr)
             throw OptionNotFound(subcom);
         return subc;
     }
     /// Get a pointer to subcommand by index
     App *get_subcommand(int index = 0) const {
         if(index >= 0) {
             auto uindex = static_cast<unsigned>(index);
             if(uindex < subcommands_.size())
                 return subcommands_[uindex].get();
         }
         throw OptionNotFound(std::to_string(index));
     }
 
     /// Check to see if a subcommand is part of this command and get a shared_ptr to it
     CLI::App_p get_subcommand_ptr(App *subcom) const {
         if(subcom == nullptr)
             throw OptionNotFound("nullptr passed");
         for(const App_p &subcomptr : subcommands_)
             if(subcomptr.get() == subcom)
                 return subcomptr;
         throw OptionNotFound(subcom->get_name());
     }
 
     /// Check to see if a subcommand is part of this command (text version)
     CLI::App_p get_subcommand_ptr(std::string subcom) const {
         for(const App_p &subcomptr : subcommands_)
             if(subcomptr->check_name(subcom))
                 return subcomptr;
         throw OptionNotFound(subcom);
     }
 
     /// Get an owning pointer to subcommand by index
     CLI::App_p get_subcommand_ptr(int index = 0) const {
         if(index >= 0) {
             auto uindex = static_cast<unsigned>(index);
             if(uindex < subcommands_.size())
                 return subcommands_[uindex];
         }
         throw OptionNotFound(std::to_string(index));
     }
 
     /// Check to see if an option group is part of this App
     App *get_option_group(std::string group_name) const {
         for(const App_p &app : subcommands_) {
             if(app->name_.empty() && app->group_ == group_name) {
                 return app.get();
             }
         }
         throw OptionNotFound(group_name);
     }
 
     /// No argument version of count counts the number of times this subcommand was
     /// passed in. The main app will return 1. Unnamed subcommands will also return 1 unless
     /// otherwise modified in a callback
     std::size_t count() const { return parsed_; }
 
     /// Get a count of all the arguments processed in options and subcommands, this excludes arguments which were
     /// treated as extras.
     std::size_t count_all() const {
         std::size_t cnt{0};
         for(auto &opt : options_) {
             cnt += opt->count();
         }
         for(auto &sub : subcommands_) {
             cnt += sub->count_all();
         }
         if(!get_name().empty()) {  // for named subcommands add the number of times the subcommand was called
             cnt += parsed_;
         }
         return cnt;
     }
 
     /// Changes the group membership
     App *group(std::string group_name) {
         group_ = group_name;
         return this;
     }
 
     /// The argumentless form of require subcommand requires 1 or more subcommands
     App *require_subcommand() {
         require_subcommand_min_ = 1;
         require_subcommand_max_ = 0;
         return this;
     }
 
     /// Require a subcommand to be given (does not affect help call)
     /// The number required can be given. Negative values indicate maximum
     /// number allowed (0 for any number). Max number inheritable.
     App *require_subcommand(int value) {
         if(value < 0) {
             require_subcommand_min_ = 0;
             require_subcommand_max_ = static_cast<std::size_t>(-value);
         } else {
             require_subcommand_min_ = static_cast<std::size_t>(value);
             require_subcommand_max_ = static_cast<std::size_t>(value);
         }
         return this;
     }
 
     /// Explicitly control the number of subcommands required. Setting 0
     /// for the max means unlimited number allowed. Max number inheritable.
     App *require_subcommand(std::size_t min, std::size_t max) {
         require_subcommand_min_ = min;
         require_subcommand_max_ = max;
         return this;
     }
 
     /// The argumentless form of require option requires 1 or more options be used
     App *require_option() {
         require_option_min_ = 1;
         require_option_max_ = 0;
         return this;
     }
 
     /// Require an option to be given (does not affect help call)
     /// The number required can be given. Negative values indicate maximum
     /// number allowed (0 for any number).
     App *require_option(int value) {
         if(value < 0) {
             require_option_min_ = 0;
             require_option_max_ = static_cast<std::size_t>(-value);
         } else {
             require_option_min_ = static_cast<std::size_t>(value);
             require_option_max_ = static_cast<std::size_t>(value);
         }
         return this;
     }
 
     /// Explicitly control the number of options required. Setting 0
     /// for the max means unlimited number allowed. Max number inheritable.
     App *require_option(std::size_t min, std::size_t max) {
         require_option_min_ = min;
         require_option_max_ = max;
         return this;
     }
 
     /// Stop subcommand fallthrough, so that parent commands cannot collect commands after subcommand.
     /// Default from parent, usually set on parent.
     App *fallthrough(bool value = true) {
         fallthrough_ = value;
         return this;
     }
 
     /// Check to see if this subcommand was parsed, true only if received on command line.
     /// This allows the subcommand to be directly checked.
     explicit operator bool() const { return parsed_ > 0; }
 
     ///@}
     /// @name Extras for subclassing
     ///@{
 
     /// This allows subclasses to inject code before callbacks but after parse.
     ///
     /// This does not run if any errors or help is thrown.
     virtual void pre_callback() {}
 
     ///@}
     /// @name Parsing
     ///@{
     //
     /// Reset the parsed data
     void clear() {
 
         parsed_ = 0;
         pre_parse_called_ = false;
 
         missing_.clear();
         parsed_subcommands_.clear();
         for(const Option_p &opt : options_) {
             opt->clear();
         }
         for(const App_p &subc : subcommands_) {
             subc->clear();
         }
     }
 
     /// Parses the command line - throws errors.
     /// This must be called after the options are in but before the rest of the program.
     void parse(int argc, const char *const *argv) {
         // If the name is not set, read from command line
         if(name_.empty() || has_automatic_name_) {
             has_automatic_name_ = true;
             name_ = argv[0];
         }
 
         std::vector<std::string> args;
         args.reserve(static_cast<std::size_t>(argc) - 1);
         for(int i = argc - 1; i > 0; i--)
             args.emplace_back(argv[i]);
         parse(std::move(args));
     }
 
     /// Parse a single string as if it contained command line arguments.
     /// This function splits the string into arguments then calls parse(std::vector<std::string> &)
     /// the function takes an optional boolean argument specifying if the programName is included in the string to
     /// process
     void parse(std::string commandline, bool program_name_included = false) {
 
         if(program_name_included) {
             auto nstr = detail::split_program_name(commandline);
             if((name_.empty()) || (has_automatic_name_)) {
                 has_automatic_name_ = true;
                 name_ = nstr.first;
             }
             commandline = std::move(nstr.second);
         } else {
             detail::trim(commandline);
         }
         // the next section of code is to deal with quoted arguments after an '=' or ':' for windows like operations
         if(!commandline.empty()) {
             commandline = detail::find_and_modify(commandline, "=", detail::escape_detect);
             if(allow_windows_style_options_)
                 commandline = detail::find_and_modify(commandline, ":", detail::escape_detect);
         }
 
         auto args = detail::split_up(std::move(commandline));
         // remove all empty strings
         args.erase(std::remove(args.begin(), args.end(), std::string{}), args.end());
         std::reverse(args.begin(), args.end());
 
         parse(std::move(args));
     }
 
     /// The real work is done here. Expects a reversed vector.
     /// Changes the vector to the remaining options.
     void parse(std::vector<std::string> &args) {
         // Clear if parsed
         if(parsed_ > 0)
             clear();
 
         // parsed_ is incremented in commands/subcommands,
         // but placed here to make sure this is cleared when
         // running parse after an error is thrown, even by _validate or _configure.
         parsed_ = 1;
         _validate();
         _configure();
         // set the parent as nullptr as this object should be the top now
         parent_ = nullptr;
         parsed_ = 0;
 
         _parse(args);
         run_callback();
     }
 
     /// The real work is done here. Expects a reversed vector.
     void parse(std::vector<std::string> &&args) {
         // Clear if parsed
         if(parsed_ > 0)
             clear();
 
         // parsed_ is incremented in commands/subcommands,
         // but placed here to make sure this is cleared when
         // running parse after an error is thrown, even by _validate or _configure.
         parsed_ = 1;
         _validate();
         _configure();
         // set the parent as nullptr as this object should be the top now
         parent_ = nullptr;
         parsed_ = 0;
 
         _parse(std::move(args));
         run_callback();
     }
 
     /// Provide a function to print a help message. The function gets access to the App pointer and error.
     void failure_message(std::function<std::string(const App *, const Error &e)> function) {
         failure_message_ = function;
     }
 
     /// Print a nice error message and return the exit code
     int exit(const Error &e, std::ostream &out = std::cout, std::ostream &err = std::cerr) const {
 
         /// Avoid printing anything if this is a CLI::RuntimeError
         if(e.get_name() == "RuntimeError")
             return e.get_exit_code();
 
         if(e.get_name() == "CallForHelp") {
             out << help();
             return e.get_exit_code();
         }
 
         if(e.get_name() == "CallForAllHelp") {
             out << help("", AppFormatMode::All);
             return e.get_exit_code();
         }
 
         if(e.get_name() == "CallForVersion") {
             out << e.what() << std::endl;
             return e.get_exit_code();
         }
 
         if(e.get_exit_code() != static_cast<int>(ExitCodes::Success)) {
             if(failure_message_)
                 err << failure_message_(this, e) << std::flush;
         }
 
         return e.get_exit_code();
     }
 
     ///@}
     /// @name Post parsing
     ///@{
 
     /// Counts the number of times the given option was passed.
     std::size_t count(std::string option_name) const { return get_option(option_name)->count(); }
 
     /// Get a subcommand pointer list to the currently selected subcommands (after parsing by default, in command
     /// line order; use parsed = false to get the original definition list.)
     std::vector<App *> get_subcommands() const { return parsed_subcommands_; }
 
     /// Get a filtered subcommand pointer list from the original definition list. An empty function will provide all
     /// subcommands (const)
     std::vector<const App *> get_subcommands(const std::function<bool(const App *)> &filter) const {
         std::vector<const App *> subcomms(subcommands_.size());
         std::transform(std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms), [](const App_p &v) {
             return v.get();
         });
 
         if(filter) {
             subcomms.erase(std::remove_if(std::begin(subcomms),
                                           std::end(subcomms),
                                           [&filter](const App *app) { return !filter(app); }),
                            std::end(subcomms));
         }
 
         return subcomms;
     }
 
     /// Get a filtered subcommand pointer list from the original definition list. An empty function will provide all
     /// subcommands
     std::vector<App *> get_subcommands(const std::function<bool(App *)> &filter) {
         std::vector<App *> subcomms(subcommands_.size());
         std::transform(std::begin(subcommands_), std::end(subcommands_), std::begin(subcomms), [](const App_p &v) {
             return v.get();
         });
 
         if(filter) {
             subcomms.erase(
                 std::remove_if(std::begin(subcomms), std::end(subcomms), [&filter](App *app) { return !filter(app); }),
                 std::end(subcomms));
         }
 
         return subcomms;
     }
 
     /// Check to see if given subcommand was selected
     bool got_subcommand(const App *subcom) const {
         // get subcom needed to verify that this was a real subcommand
         return get_subcommand(subcom)->parsed_ > 0;
     }
 
     /// Check with name instead of pointer to see if subcommand was selected
     bool got_subcommand(std::string subcommand_name) const { return get_subcommand(subcommand_name)->parsed_ > 0; }
 
     /// Sets excluded options for the subcommand
     App *excludes(Option *opt) {
         if(opt == nullptr) {
             throw OptionNotFound("nullptr passed");
         }
         exclude_options_.insert(opt);
         return this;
     }
 
     /// Sets excluded subcommands for the subcommand
     App *excludes(App *app) {
         if(app == nullptr) {
             throw OptionNotFound("nullptr passed");
         }
         if(app == this) {
             throw OptionNotFound("cannot self reference in needs");
         }
         auto res = exclude_subcommands_.insert(app);
         // subcommand exclusion should be symmetric
         if(res.second) {
             app->exclude_subcommands_.insert(this);
         }
         return this;
     }
 
     App *needs(Option *opt) {
         if(opt == nullptr) {
             throw OptionNotFound("nullptr passed");
         }
         need_options_.insert(opt);
         return this;
     }
 
     App *needs(App *app) {
         if(app == nullptr) {
             throw OptionNotFound("nullptr passed");
         }
         if(app == this) {
             throw OptionNotFound("cannot self reference in needs");
         }
         need_subcommands_.insert(app);
         return this;
     }
 
     /// Removes an option from the excludes list of this subcommand
     bool remove_excludes(Option *opt) {
         auto iterator = std::find(std::begin(exclude_options_), std::end(exclude_options_), opt);
         if(iterator == std::end(exclude_options_)) {
             return false;
         }
         exclude_options_.erase(iterator);
         return true;
     }
 
     /// Removes a subcommand from the excludes list of this subcommand
     bool remove_excludes(App *app) {
         auto iterator = std::find(std::begin(exclude_subcommands_), std::end(exclude_subcommands_), app);
         if(iterator == std::end(exclude_subcommands_)) {
             return false;
         }
         auto other_app = *iterator;
         exclude_subcommands_.erase(iterator);
         other_app->remove_excludes(this);
         return true;
     }
 
     /// Removes an option from the needs list of this subcommand
     bool remove_needs(Option *opt) {
         auto iterator = std::find(std::begin(need_options_), std::end(need_options_), opt);
         if(iterator == std::end(need_options_)) {
             return false;
         }
         need_options_.erase(iterator);
         return true;
     }
 
     /// Removes a subcommand from the needs list of this subcommand
     bool remove_needs(App *app) {
         auto iterator = std::find(std::begin(need_subcommands_), std::end(need_subcommands_), app);
         if(iterator == std::end(need_subcommands_)) {
             return false;
         }
         need_subcommands_.erase(iterator);
         return true;
     }
 
     ///@}
     /// @name Help
     ///@{
 
     /// Set footer.
     App *footer(std::string footer_string) {
         footer_ = std::move(footer_string);
         return this;
     }
     /// Set footer.
     App *footer(std::function<std::string()> footer_function) {
         footer_callback_ = std::move(footer_function);
         return this;
     }
     /// Produce a string that could be read in as a config of the current values of the App. Set default_also to
     /// include default arguments. write_descriptions will print a description for the App and for each option.
     std::string config_to_str(bool default_also = false, bool write_description = false) const {
         return config_formatter_->to_config(this, default_also, write_description, "");
     }
 
     /// Makes a help message, using the currently configured formatter
     /// Will only do one subcommand at a time
     std::string help(std::string prev = "", AppFormatMode mode = AppFormatMode::Normal) const {
         if(prev.empty())
             prev = get_name();
         else
             prev += " " + get_name();
 
         // Delegate to subcommand if needed
         auto selected_subcommands = get_subcommands();
         if(!selected_subcommands.empty()) {
             return selected_subcommands.at(0)->help(prev, mode);
         }
         return formatter_->make_help(this, prev, mode);
     }
 
     /// Displays a version string
     std::string version() const {
         std::string val;
         if(version_ptr_ != nullptr) {
             auto rv = version_ptr_->results();
             version_ptr_->clear();
             version_ptr_->add_result("true");
             try {
                 version_ptr_->run_callback();
             } catch(const CLI::CallForVersion &cfv) {
                 val = cfv.what();
             }
             version_ptr_->clear();
             version_ptr_->add_result(rv);
         }
         return val;
     }
     ///@}
     /// @name Getters
     ///@{
 
     /// Access the formatter
     std::shared_ptr<FormatterBase> get_formatter() const { return formatter_; }
 
     /// Access the config formatter
     std::shared_ptr<Config> get_config_formatter() const { return config_formatter_; }
 
     /// Access the config formatter as a configBase pointer
     std::shared_ptr<ConfigBase> get_config_formatter_base() const {
         // This is safer as a dynamic_cast if we have RTTI, as Config -> ConfigBase
 #if defined(__cpp_rtti) || (defined(__GXX_RTTI) && __GXX_RTTI) || (defined(_HAS_STATIC_RTTI) && (_HAS_STATIC_RTTI == 0))
         return std::dynamic_pointer_cast<ConfigBase>(config_formatter_);
 #else
         return std::static_pointer_cast<ConfigBase>(config_formatter_);
 #endif
     }
 
     /// Get the app or subcommand description
     std::string get_description() const { return description_; }
 
     /// Set the description of the app
     App *description(std::string app_description) {
         description_ = std::move(app_description);
         return this;
     }
 
     /// Get the list of options (user facing function, so returns raw pointers), has optional filter function
     std::vector<const Option *> get_options(const std::function<bool(const Option *)> filter = {}) const {
         std::vector<const Option *> options(options_.size());
         std::transform(std::begin(options_), std::end(options_), std::begin(options), [](const Option_p &val) {
             return val.get();
         });
 
         if(filter) {
             options.erase(std::remove_if(std::begin(options),
                                          std::end(options),
                                          [&filter](const Option *opt) { return !filter(opt); }),
                           std::end(options));
         }
 
         return options;
     }
 
     /// Non-const version of the above
     std::vector<Option *> get_options(const std::function<bool(Option *)> filter = {}) {
         std::vector<Option *> options(options_.size());
         std::transform(std::begin(options_), std::end(options_), std::begin(options), [](const Option_p &val) {
             return val.get();
         });
 
         if(filter) {
             options.erase(
                 std::remove_if(std::begin(options), std::end(options), [&filter](Option *opt) { return !filter(opt); }),
                 std::end(options));
         }
 
         return options;
     }
 
     /// Get an option by name (noexcept non-const version)
     Option *get_option_no_throw(std::string option_name) noexcept {
         for(Option_p &opt : options_) {
             if(opt->check_name(option_name)) {
                 return opt.get();
             }
         }
         for(auto &subc : subcommands_) {
             // also check down into nameless subcommands
             if(subc->get_name().empty()) {
                 auto opt = subc->get_option_no_throw(option_name);
                 if(opt != nullptr) {
                     return opt;
                 }
             }
         }
         return nullptr;
     }
 
     /// Get an option by name (noexcept const version)
     const Option *get_option_no_throw(std::string option_name) const noexcept {
         for(const Option_p &opt : options_) {
             if(opt->check_name(option_name)) {
                 return opt.get();
             }
         }
         for(const auto &subc : subcommands_) {
             // also check down into nameless subcommands
             if(subc->get_name().empty()) {
                 auto opt = subc->get_option_no_throw(option_name);
                 if(opt != nullptr) {
                     return opt;
                 }
             }
         }
         return nullptr;
     }
 
     /// Get an option by name
     const Option *get_option(std::string option_name) const {
         auto opt = get_option_no_throw(option_name);
         if(opt == nullptr) {
             throw OptionNotFound(option_name);
         }
         return opt;
     }
 
     /// Get an option by name (non-const version)
     Option *get_option(std::string option_name) {
         auto opt = get_option_no_throw(option_name);
         if(opt == nullptr) {
             throw OptionNotFound(option_name);
         }
         return opt;
     }
 
     /// Shortcut bracket operator for getting a pointer to an option
     const Option *operator[](const std::string &option_name) const { return get_option(option_name); }
 
     /// Shortcut bracket operator for getting a pointer to an option
     const Option *operator[](const char *option_name) const { return get_option(option_name); }
 
     /// Check the status of ignore_case
     bool get_ignore_case() const { return ignore_case_; }
 
     /// Check the status of ignore_underscore
     bool get_ignore_underscore() const { return ignore_underscore_; }
 
     /// Check the status of fallthrough
     bool get_fallthrough() const { return fallthrough_; }
 
     /// Check the status of the allow windows style options
     bool get_allow_windows_style_options() const { return allow_windows_style_options_; }
 
     /// Check the status of the allow windows style options
     bool get_positionals_at_end() const { return positionals_at_end_; }
 
     /// Check the status of the allow windows style options
     bool get_configurable() const { return configurable_; }
 
     /// Get the group of this subcommand
     const std::string &get_group() const { return group_; }
 
     /// Generate and return the footer.
     std::string get_footer() const { return (footer_callback_) ? footer_callback_() + '\n' + footer_ : footer_; }
 
     /// Get the required min subcommand value
     std::size_t get_require_subcommand_min() const { return require_subcommand_min_; }
 
     /// Get the required max subcommand value
     std::size_t get_require_subcommand_max() const { return require_subcommand_max_; }
 
     /// Get the required min option value
     std::size_t get_require_option_min() const { return require_option_min_; }
 
     /// Get the required max option value
     std::size_t get_require_option_max() const { return require_option_max_; }
 
     /// Get the prefix command status
     bool get_prefix_command() const { return prefix_command_; }
 
     /// Get the status of allow extras
     bool get_allow_extras() const { return allow_extras_; }
 
     /// Get the status of required
     bool get_required() const { return required_; }
 
     /// Get the status of disabled
     bool get_disabled() const { return disabled_; }
 
     /// Get the status of silence
     bool get_silent() const { return silent_; }
 
     /// Get the status of disabled
     bool get_immediate_callback() const { return immediate_callback_; }
 
     /// Get the status of disabled by default
     bool get_disabled_by_default() const { return (default_startup == startup_mode::disabled); }
 
     /// Get the status of disabled by default
     bool get_enabled_by_default() const { return (default_startup == startup_mode::enabled); }
     /// Get the status of validating positionals
     bool get_validate_positionals() const { return validate_positionals_; }
 
     /// Get the status of allow extras
     config_extras_mode get_allow_config_extras() const { return allow_config_extras_; }
 
     /// Get a pointer to the help flag.
     Option *get_help_ptr() { return help_ptr_; }
 
     /// Get a pointer to the help flag. (const)
     const Option *get_help_ptr() const { return help_ptr_; }
 
     /// Get a pointer to the help all flag. (const)
     const Option *get_help_all_ptr() const { return help_all_ptr_; }
 
     /// Get a pointer to the config option.
     Option *get_config_ptr() { return config_ptr_; }
 
     /// Get a pointer to the config option. (const)
     const Option *get_config_ptr() const { return config_ptr_; }
 
     /// Get a pointer to the version option.
     Option *get_version_ptr() { return version_ptr_; }
 
     /// Get a pointer to the version option. (const)
     const Option *get_version_ptr() const { return version_ptr_; }
 
     /// Get the parent of this subcommand (or nullptr if master app)
     App *get_parent() { return parent_; }
 
     /// Get the parent of this subcommand (or nullptr if master app) (const version)
     const App *get_parent() const { return parent_; }
 
     /// Get the name of the current app
     const std::string &get_name() const { return name_; }
 
     /// Get the aliases of the current app
     const std::vector<std::string> &get_aliases() const { return aliases_; }
 
     /// clear all the aliases of the current App
     App *clear_aliases() {
         aliases_.clear();
         return this;
     }
 
     /// Get a display name for an app
     std::string get_display_name(bool with_aliases = false) const {
         if(name_.empty()) {
             return std::string("[Option Group: ") + get_group() + "]";
         }
         if(aliases_.empty() || !with_aliases || aliases_.empty()) {
             return name_;
         }
         std::string dispname = name_;
         for(const auto &lalias : aliases_) {
             dispname.push_back(',');
             dispname.push_back(' ');
             dispname.append(lalias);
         }
         return dispname;
     }
 
     /// Check the name, case insensitive and underscore insensitive if set
     bool check_name(std::string name_to_check) const {
         std::string local_name = name_;
         if(ignore_underscore_) {
             local_name = detail::remove_underscore(name_);
             name_to_check = detail::remove_underscore(name_to_check);
         }
         if(ignore_case_) {
             local_name = detail::to_lower(name_);
             name_to_check = detail::to_lower(name_to_check);
         }
 
         if(local_name == name_to_check) {
             return true;
         }
         for(auto les : aliases_) {
             if(ignore_underscore_) {
                 les = detail::remove_underscore(les);
             }
             if(ignore_case_) {
                 les = detail::to_lower(les);
             }
             if(les == name_to_check) {
                 return true;
             }
         }
         return false;
     }
 
     /// Get the groups available directly from this option (in order)
     std::vector<std::string> get_groups() const {
         std::vector<std::string> groups;
 
         for(const Option_p &opt : options_) {
             // Add group if it is not already in there
             if(std::find(groups.begin(), groups.end(), opt->get_group()) == groups.end()) {
                 groups.push_back(opt->get_group());
             }
         }
 
         return groups;
     }
 
     /// This gets a vector of pointers with the original parse order
     const std::vector<Option *> &parse_order() const { return parse_order_; }
 
     /// This returns the missing options from the current subcommand
     std::vector<std::string> remaining(bool recurse = false) const {
         std::vector<std::string> miss_list;
         for(const std::pair<detail::Classifier, std::string> &miss : missing_) {
             miss_list.push_back(std::get<1>(miss));
         }
         // Get from a subcommand that may allow extras
         if(recurse) {
             if(!allow_extras_) {
                 for(const auto &sub : subcommands_) {
                     if(sub->name_.empty() && !sub->missing_.empty()) {
                         for(const std::pair<detail::Classifier, std::string> &miss : sub->missing_) {
                             miss_list.push_back(std::get<1>(miss));
                         }
                     }
                 }
             }
             // Recurse into subcommands
 
             for(const App *sub : parsed_subcommands_) {
                 std::vector<std::string> output = sub->remaining(recurse);
                 std::copy(std::begin(output), std::end(output), std::back_inserter(miss_list));
             }
         }
         return miss_list;
     }
 
     /// This returns the missing options in a form ready for processing by another command line program
     std::vector<std::string> remaining_for_passthrough(bool recurse = false) const {
         std::vector<std::string> miss_list = remaining(recurse);
         std::reverse(std::begin(miss_list), std::end(miss_list));
         return miss_list;
     }
 
     /// This returns the number of remaining options, minus the -- separator
     std::size_t remaining_size(bool recurse = false) const {
         auto remaining_options = static_cast<std::size_t>(std::count_if(
             std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifier, std::string> &val) {
                 return val.first != detail::Classifier::POSITIONAL_MARK;
             }));
 
         if(recurse) {
             for(const App_p &sub : subcommands_) {
                 remaining_options += sub->remaining_size(recurse);
             }
         }
         return remaining_options;
     }
 
     ///@}
 
   protected:
     /// Check the options to make sure there are no conflicts.
     ///
     /// Currently checks to see if multiple positionals exist with unlimited args and checks if the min and max options
     /// are feasible
     void _validate() const {
         // count the number of positional only args
         auto pcount = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
             return opt->get_items_expected_max() >= detail::expected_max_vector_size && !opt->nonpositional();
         });
         if(pcount > 1) {
             auto pcount_req = std::count_if(std::begin(options_), std::end(options_), [](const Option_p &opt) {
                 return opt->get_items_expected_max() >= detail::expected_max_vector_size && !opt->nonpositional() &&
                        opt->get_required();
             });
             if(pcount - pcount_req > 1) {
                 throw InvalidError(name_);
             }
         }
 
         std::size_t nameless_subs{0};
         for(const App_p &app : subcommands_) {
             app->_validate();
             if(app->get_name().empty())
                 ++nameless_subs;
         }
 
         if(require_option_min_ > 0) {
             if(require_option_max_ > 0) {
                 if(require_option_max_ < require_option_min_) {
                     throw(InvalidError("Required min options greater than required max options",
                                        ExitCodes::InvalidError));
                 }
             }
             if(require_option_min_ > (options_.size() + nameless_subs)) {
                 throw(InvalidError("Required min options greater than number of available options",
                                    ExitCodes::InvalidError));
             }
         }
     }
 
     /// configure subcommands to enable parsing through the current object
     /// set the correct fallthrough and prefix for nameless subcommands and manage the automatic enable or disable
     /// makes sure parent is set correctly
     void _configure() {
         if(default_startup == startup_mode::enabled) {
             disabled_ = false;
         } else if(default_startup == startup_mode::disabled) {
             disabled_ = true;
         }
         for(const App_p &app : subcommands_) {
             if(app->has_automatic_name_) {
                 app->name_.clear();
             }
             if(app->name_.empty()) {
                 app->fallthrough_ = false;  // make sure fallthrough_ is false to prevent infinite loop
                 app->prefix_command_ = false;
             }
             // make sure the parent is set to be this object in preparation for parse
             app->parent_ = this;
             app->_configure();
         }
     }
 
     /// Internal function to run (App) callback, bottom up
     void run_callback(bool final_mode = false, bool suppress_final_callback = false) {
         pre_callback();
         // in the main app if immediate_callback_ is set it runs the main callback before the used subcommands
         if(!final_mode && parse_complete_callback_) {
             parse_complete_callback_();
         }
         // run the callbacks for the received subcommands
         for(App *subc : get_subcommands()) {
             subc->run_callback(true, suppress_final_callback);
         }
         // now run callbacks for option_groups
         for(auto &subc : subcommands_) {
             if(subc->name_.empty() && subc->count_all() > 0) {
                 subc->run_callback(true, suppress_final_callback);
             }
         }
 
         // finally run the main callback
         if(final_callback_ && (parsed_ > 0) && (!suppress_final_callback)) {
             if(!name_.empty() || count_all() > 0 || parent_ == nullptr) {
                 final_callback_();
             }
         }
     }
 
     /// Check to see if a subcommand is valid. Give up immediately if subcommand max has been reached.
     bool _valid_subcommand(const std::string &current, bool ignore_used = true) const {
         // Don't match if max has been reached - but still check parents
         if(require_subcommand_max_ != 0 && parsed_subcommands_.size() >= require_subcommand_max_) {
             return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
         }
         auto com = _find_subcommand(current, true, ignore_used);
         if(com != nullptr) {
             return true;
         }
         // Check parent if exists, else return false
         return parent_ != nullptr && parent_->_valid_subcommand(current, ignore_used);
     }
 
     /// Selects a Classifier enum based on the type of the current argument
     detail::Classifier _recognize(const std::string &current, bool ignore_used_subcommands = true) const {
         std::string dummy1, dummy2;
 
         if(current == "--")
             return detail::Classifier::POSITIONAL_MARK;
         if(_valid_subcommand(current, ignore_used_subcommands))
             return detail::Classifier::SUBCOMMAND;
         if(detail::split_long(current, dummy1, dummy2))
             return detail::Classifier::LONG;
         if(detail::split_short(current, dummy1, dummy2)) {
             if(dummy1[0] >= '0' && dummy1[0] <= '9') {
                 if(get_option_no_throw(std::string{'-', dummy1[0]}) == nullptr) {
                     return detail::Classifier::NONE;
                 }
             }
             return detail::Classifier::SHORT;
         }
         if((allow_windows_style_options_) && (detail::split_windows_style(current, dummy1, dummy2)))
             return detail::Classifier::WINDOWS_STYLE;
         if((current == "++") && !name_.empty() && parent_ != nullptr)
             return detail::Classifier::SUBCOMMAND_TERMINATOR;
         return detail::Classifier::NONE;
     }
 
     // The parse function is now broken into several parts, and part of process
 
     /// Read and process a configuration file (main app only)
     void _process_config_file() {
         if(config_ptr_ != nullptr) {
             bool config_required = config_ptr_->get_required();
             auto file_given = config_ptr_->count() > 0;
             auto config_files = config_ptr_->as<std::vector<std::string>>();
             if(config_files.empty() || config_files.front().empty()) {
                 if(config_required) {
                     throw FileError::Missing("no specified config file");
                 }
                 return;
             }
             for(auto rit = config_files.rbegin(); rit != config_files.rend(); ++rit) {
                 const auto &config_file = *rit;
                 auto path_result = detail::check_path(config_file.c_str());
                 if(path_result == detail::path_type::file) {
                     try {
                         std::vector<ConfigItem> values = config_formatter_->from_file(config_file);
                         _parse_config(values);
                         if(!file_given) {
                             config_ptr_->add_result(config_file);
                         }
                     } catch(const FileError &) {
                         if(config_required || file_given)
                             throw;
                     }
                 } else if(config_required || file_given) {
                     throw FileError::Missing(config_file);
                 }
             }
         }
     }
 
     /// Get envname options if not yet passed. Runs on *all* subcommands.
     void _process_env() {
         for(const Option_p &opt : options_) {
             if(opt->count() == 0 && !opt->envname_.empty()) {
                 char *buffer = nullptr;
                 std::string ename_string;
 
 #ifdef _MSC_VER
                 // Windows version
                 std::size_t sz = 0;
                 if(_dupenv_s(&buffer, &sz, opt->envname_.c_str()) == 0 && buffer != nullptr) {
                     ename_string = std::string(buffer);
                     free(buffer);
                 }
 #else
                 // This also works on Windows, but gives a warning
                 buffer = std::getenv(opt->envname_.c_str());
                 if(buffer != nullptr)
                     ename_string = std::string(buffer);
 #endif
 
                 if(!ename_string.empty()) {
                     opt->add_result(ename_string);
                 }
             }
         }
 
         for(App_p &sub : subcommands_) {
             if(sub->get_name().empty() || !sub->parse_complete_callback_)
                 sub->_process_env();
         }
     }
 
     /// Process callbacks. Runs on *all* subcommands.
     void _process_callbacks() {
 
         for(App_p &sub : subcommands_) {
             // process the priority option_groups first
             if(sub->get_name().empty() && sub->parse_complete_callback_) {
                 if(sub->count_all() > 0) {
                     sub->_process_callbacks();
                     sub->run_callback();
                 }
             }
         }
 
         for(const Option_p &opt : options_) {
             if(opt->count() > 0 && !opt->get_callback_run()) {
                 opt->run_callback();
             }
         }
         for(App_p &sub : subcommands_) {
             if(!sub->parse_complete_callback_) {
                 sub->_process_callbacks();
             }
         }
     }
 
     /// Run help flag processing if any are found.
     ///
     /// The flags allow recursive calls to remember if there was a help flag on a parent.
     void _process_help_flags(bool trigger_help = false, bool trigger_all_help = false) const {
         const Option *help_ptr = get_help_ptr();
         const Option *help_all_ptr = get_help_all_ptr();
 
         if(help_ptr != nullptr && help_ptr->count() > 0)
             trigger_help = true;
         if(help_all_ptr != nullptr && help_all_ptr->count() > 0)
             trigger_all_help = true;
 
         // If there were parsed subcommands, call those. First subcommand wins if there are multiple ones.
         if(!parsed_subcommands_.empty()) {
             for(const App *sub : parsed_subcommands_)
                 sub->_process_help_flags(trigger_help, trigger_all_help);
 
             // Only the final subcommand should call for help. All help wins over help.
         } else if(trigger_all_help) {
             throw CallForAllHelp();
         } else if(trigger_help) {
             throw CallForHelp();
         }
     }
 
     /// Verify required options and cross requirements. Subcommands too (only if selected).
     void _process_requirements() {
         // check excludes
         bool excluded{false};
         std::string excluder;
         for(auto &opt : exclude_options_) {
             if(opt->count() > 0) {
                 excluded = true;
                 excluder = opt->get_name();
             }
         }
         for(auto &subc : exclude_subcommands_) {
             if(subc->count_all() > 0) {
                 excluded = true;
                 excluder = subc->get_display_name();
             }
         }
         if(excluded) {
             if(count_all() > 0) {
                 throw ExcludesError(get_display_name(), excluder);
             }
             // if we are excluded but didn't receive anything, just return
             return;
         }
 
         // check excludes
         bool missing_needed{false};
         std::string missing_need;
         for(auto &opt : need_options_) {
             if(opt->count() == 0) {
                 missing_needed = true;
                 missing_need = opt->get_name();
             }
         }
         for(auto &subc : need_subcommands_) {
             if(subc->count_all() == 0) {
                 missing_needed = true;
                 missing_need = subc->get_display_name();
             }
         }
         if(missing_needed) {
             if(count_all() > 0) {
                 throw RequiresError(get_display_name(), missing_need);
             }
             // if we missing something but didn't have any options, just return
             return;
         }
 
         std::size_t used_options = 0;
         for(const Option_p &opt : options_) {
 
             if(opt->count() != 0) {
                 ++used_options;
             }
             // Required but empty
             if(opt->get_required() && opt->count() == 0) {
                 throw RequiredError(opt->get_name());
             }
             // Requires
             for(const Option *opt_req : opt->needs_)
                 if(opt->count() > 0 && opt_req->count() == 0)
                     throw RequiresError(opt->get_name(), opt_req->get_name());
             // Excludes
             for(const Option *opt_ex : opt->excludes_)
                 if(opt->count() > 0 && opt_ex->count() != 0)
                     throw ExcludesError(opt->get_name(), opt_ex->get_name());
         }
         // check for the required number of subcommands
         if(require_subcommand_min_ > 0) {
             auto selected_subcommands = get_subcommands();
             if(require_subcommand_min_ > selected_subcommands.size())
                 throw RequiredError::Subcommand(require_subcommand_min_);
         }
 
         // Max error cannot occur, the extra subcommand will parse as an ExtrasError or a remaining item.
 
         // run this loop to check how many unnamed subcommands were actually used since they are considered options
         // from the perspective of an App
         for(App_p &sub : subcommands_) {
             if(sub->disabled_)
                 continue;
             if(sub->name_.empty() && sub->count_all() > 0) {
                 ++used_options;
             }
         }
 
         if(require_option_min_ > used_options || (require_option_max_ > 0 && require_option_max_ < used_options)) {
             auto option_list = detail::join(options_, [this](const Option_p &ptr) {
                 if(ptr.get() == help_ptr_ || ptr.get() == help_all_ptr_) {
                     return std::string{};
                 }
                 return ptr->get_name(false, true);
             });
 
             auto subc_list = get_subcommands([](App *app) { return ((app->get_name().empty()) && (!app->disabled_)); });
             if(!subc_list.empty()) {
                 option_list += "," + detail::join(subc_list, [](const App *app) { return app->get_display_name(); });
             }
             throw RequiredError::Option(require_option_min_, require_option_max_, used_options, option_list);
         }
 
         // now process the requirements for subcommands if needed
         for(App_p &sub : subcommands_) {
             if(sub->disabled_)
                 continue;
             if(sub->name_.empty() && sub->required_ == false) {
                 if(sub->count_all() == 0) {
                     if(require_option_min_ > 0 && require_option_min_ <= used_options) {
                         continue;
                         // if we have met the requirement and there is nothing in this option group skip checking
                         // requirements
                     }
                     if(require_option_max_ > 0 && used_options >= require_option_min_) {
                         continue;
                         // if we have met the requirement and there is nothing in this option group skip checking
                         // requirements
                     }
                 }
             }
             if(sub->count() > 0 || sub->name_.empty()) {
                 sub->_process_requirements();
             }
 
             if(sub->required_ && sub->count_all() == 0) {
                 throw(CLI::RequiredError(sub->get_display_name()));
             }
         }
     }
 
     /// Process callbacks and such.
     void _process() {
         CLI::FileError fe("ne");
         bool caught_error{false};
         try {
             // the config file might generate a FileError but that should not be processed until later in the process
             // to allow for help, version and other errors to generate first.
             _process_config_file();
             // process env shouldn't throw but no reason to process it if config generated an error
             _process_env();
         } catch(const CLI::FileError &fe2) {
             fe = fe2;
             caught_error = true;
         }
         // callbacks and help_flags can generate exceptions which should take priority over the config file error if one
         // exists
         _process_callbacks();
         _process_help_flags();
 
         if(caught_error) {
             throw CLI::FileError(std::move(fe));
         }
 
         _process_requirements();
     }
 
     /// Throw an error if anything is left over and should not be.
     void _process_extras() {
         if(!(allow_extras_ || prefix_command_)) {
             std::size_t num_left_over = remaining_size();
             if(num_left_over > 0) {
                 throw ExtrasError(name_, remaining(false));
             }
         }
 
         for(App_p &sub : subcommands_) {
             if(sub->count() > 0)
                 sub->_process_extras();
         }
     }
 
     /// Throw an error if anything is left over and should not be.
     /// Modifies the args to fill in the missing items before throwing.
     void _process_extras(std::vector<std::string> &args) {
         if(!(allow_extras_ || prefix_command_)) {
             std::size_t num_left_over = remaining_size();
             if(num_left_over > 0) {
                 args = remaining(false);
                 throw ExtrasError(name_, args);
             }
         }
 
         for(App_p &sub : subcommands_) {
             if(sub->count() > 0)
                 sub->_process_extras(args);
         }
     }
 
     /// Internal function to recursively increment the parsed counter on the current app as well unnamed subcommands
     void increment_parsed() {
         ++parsed_;
         for(App_p &sub : subcommands_) {
             if(sub->get_name().empty())
                 sub->increment_parsed();
         }
     }
     /// Internal parse function
     void _parse(std::vector<std::string> &args) {
         increment_parsed();
         _trigger_pre_parse(args.size());
         bool positional_only = false;
 
         while(!args.empty()) {
             if(!_parse_single(args, positional_only)) {
                 break;
             }
         }
 
         if(parent_ == nullptr) {
             _process();
 
             // Throw error if any items are left over (depending on settings)
             _process_extras(args);
 
             // Convert missing (pairs) to extras (string only) ready for processing in another app
             args = remaining_for_passthrough(false);
         } else if(parse_complete_callback_) {
             _process_env();
             _process_callbacks();
             _process_help_flags();
             _process_requirements();
             run_callback(false, true);
         }
     }
 
     /// Internal parse function
     void _parse(std::vector<std::string> &&args) {
         // this can only be called by the top level in which case parent == nullptr by definition
         // operation is simplified
         increment_parsed();
         _trigger_pre_parse(args.size());
         bool positional_only = false;
 
         while(!args.empty()) {
             _parse_single(args, positional_only);
         }
         _process();
 
         // Throw error if any items are left over (depending on settings)
         _process_extras();
     }
 
     /// Parse one config param, return false if not found in any subcommand, remove if it is
     ///
     /// If this has more than one dot.separated.name, go into the subcommand matching it
     /// Returns true if it managed to find the option, if false you'll need to remove the arg manually.
     void _parse_config(const std::vector<ConfigItem> &args) {
         for(const ConfigItem &item : args) {
             if(!_parse_single_config(item) && allow_config_extras_ == config_extras_mode::error)
                 throw ConfigError::Extras(item.fullname());
         }
     }
 
     /// Fill in a single config option
     bool _parse_single_config(const ConfigItem &item, std::size_t level = 0) {
         if(level < item.parents.size()) {
             try {
                 auto subcom = get_subcommand(item.parents.at(level));
                 auto result = subcom->_parse_single_config(item, level + 1);
 
                 return result;
             } catch(const OptionNotFound &) {
                 return false;
             }
         }
         // check for section open
         if(item.name == "++") {
             if(configurable_) {
                 increment_parsed();
                 _trigger_pre_parse(2);
                 if(parent_ != nullptr) {
                     parent_->parsed_subcommands_.push_back(this);
                 }
             }
             return true;
         }
         // check for section close
         if(item.name == "--") {
             if(configurable_) {
                 _process_callbacks();
                 _process_requirements();
                 run_callback();
             }
             return true;
         }
         Option *op = get_option_no_throw("--" + item.name);
         if(op == nullptr) {
             if(item.name.size() == 1) {
                 op = get_option_no_throw("-" + item.name);
             }
         }
         if(op == nullptr) {
             op = get_option_no_throw(item.name);
         }
         if(op == nullptr) {
             // If the option was not present
             if(get_allow_config_extras() == config_extras_mode::capture)
                 // Should we worry about classifying the extras properly?
                 missing_.emplace_back(detail::Classifier::NONE, item.fullname());
             return false;
         }
 
         if(!op->get_configurable())
             throw ConfigError::NotConfigurable(item.fullname());
 
         if(op->empty()) {
             // Flag parsing
             if(op->get_expected_min() == 0) {
                 auto res = config_formatter_->to_flag(item);
                 res = op->get_flag_value(item.name, res);
 
                 op->add_result(res);
 
             } else {
                 op->add_result(item.inputs);
                 op->run_callback();
             }
         }
 
         return true;
     }
 
     /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing
     /// from master return false if the parse has failed and needs to return to parent
     bool _parse_single(std::vector<std::string> &args, bool &positional_only) {
         bool retval = true;
         detail::Classifier classifier = positional_only ? detail::Classifier::NONE : _recognize(args.back());
         switch(classifier) {
         case detail::Classifier::POSITIONAL_MARK:
             args.pop_back();
             positional_only = true;
             if((!_has_remaining_positionals()) && (parent_ != nullptr)) {
                 retval = false;
             } else {
                 _move_to_missing(classifier, "--");
             }
             break;
         case detail::Classifier::SUBCOMMAND_TERMINATOR:
             // treat this like a positional mark if in the parent app
             args.pop_back();
             retval = false;
             break;
         case detail::Classifier::SUBCOMMAND:
             retval = _parse_subcommand(args);
             break;
         case detail::Classifier::LONG:
         case detail::Classifier::SHORT:
         case detail::Classifier::WINDOWS_STYLE:
             // If already parsed a subcommand, don't accept options_
             _parse_arg(args, classifier);
             break;
         case detail::Classifier::NONE:
             // Probably a positional or something for a parent (sub)command
             retval = _parse_positional(args, false);
             if(retval && positionals_at_end_) {
                 positional_only = true;
             }
             break;
             // LCOV_EXCL_START
         default:
             throw HorribleError("unrecognized classifier (you should not see this!)");
             // LCOV_EXCL_STOP
         }
         return retval;
     }
 
     /// Count the required remaining positional arguments
     std::size_t _count_remaining_positionals(bool required_only = false) const {
         std::size_t retval = 0;
         for(const Option_p &opt : options_) {
             if(opt->get_positional() && (!required_only || opt->get_required())) {
                 if(opt->get_items_expected_min() > 0 &&
                    static_cast<int>(opt->count()) < opt->get_items_expected_min()) {
                     retval += static_cast<std::size_t>(opt->get_items_expected_min()) - opt->count();
                 }
             }
         }
         return retval;
     }
 
     /// Count the required remaining positional arguments
     bool _has_remaining_positionals() const {
         for(const Option_p &opt : options_) {
             if(opt->get_positional() && ((static_cast<int>(opt->count()) < opt->get_items_expected_min()))) {
                 return true;
             }
         }
 
         return false;
     }
 
     /// Parse a positional, go up the tree to check
     /// @param haltOnSubcommand if set to true the operation will not process subcommands merely return false
     /// Return true if the positional was used false otherwise
     bool _parse_positional(std::vector<std::string> &args, bool haltOnSubcommand) {
 
         const std::string &positional = args.back();
 
         if(positionals_at_end_) {
             // deal with the case of required arguments at the end which should take precedence over other arguments
             auto arg_rem = args.size();
             auto remreq = _count_remaining_positionals(true);
             if(arg_rem <= remreq) {
                 for(const Option_p &opt : options_) {
                     if(opt->get_positional() && opt->required_) {
                         if(static_cast<int>(opt->count()) < opt->get_items_expected_min()) {
                             if(validate_positionals_) {
                                 std::string pos = positional;
                                 pos = opt->_validate(pos, 0);
                                 if(!pos.empty()) {
                                     continue;
                                 }
                             }
                             opt->add_result(positional);
                             parse_order_.push_back(opt.get());
                             args.pop_back();
                             return true;
                         }
                     }
                 }
             }
         }
         for(const Option_p &opt : options_) {
             // Eat options, one by one, until done
             if(opt->get_positional() &&
                (static_cast<int>(opt->count()) < opt->get_items_expected_min() || opt->get_allow_extra_args())) {
                 if(validate_positionals_) {
                     std::string pos = positional;
                     pos = opt->_validate(pos, 0);
                     if(!pos.empty()) {
                         continue;
                     }
                 }
                 opt->add_result(positional);
                 parse_order_.push_back(opt.get());
                 args.pop_back();
                 return true;
             }
         }
 
         for(auto &subc : subcommands_) {
             if((subc->name_.empty()) && (!subc->disabled_)) {
                 if(subc->_parse_positional(args, false)) {
                     if(!subc->pre_parse_called_) {
                         subc->_trigger_pre_parse(args.size());
                     }
                     return true;
                 }
             }
         }
         // let the parent deal with it if possible
         if(parent_ != nullptr && fallthrough_)
             return _get_fallthrough_parent()->_parse_positional(args, static_cast<bool>(parse_complete_callback_));
 
         /// Try to find a local subcommand that is repeated
         auto com = _find_subcommand(args.back(), true, false);
         if(com != nullptr && (require_subcommand_max_ == 0 || require_subcommand_max_ > parsed_subcommands_.size())) {
             if(haltOnSubcommand) {
                 return false;
             }
             args.pop_back();
             com->_parse(args);
             return true;
         }
         /// now try one last gasp at subcommands that have been executed before, go to root app and try to find a
         /// subcommand in a broader way, if one exists let the parent deal with it
         auto parent_app = (parent_ != nullptr) ? _get_fallthrough_parent() : this;
         com = parent_app->_find_subcommand(args.back(), true, false);
         if(com != nullptr && (com->parent_->require_subcommand_max_ == 0 ||
                               com->parent_->require_subcommand_max_ > com->parent_->parsed_subcommands_.size())) {
             return false;
         }
 
         if(positionals_at_end_) {
             throw CLI::ExtrasError(name_, args);
         }
         /// If this is an option group don't deal with it
         if(parent_ != nullptr && name_.empty()) {
             return false;
         }
         /// We are out of other options this goes to missing
         _move_to_missing(detail::Classifier::NONE, positional);
         args.pop_back();
         if(prefix_command_) {
             while(!args.empty()) {
                 _move_to_missing(detail::Classifier::NONE, args.back());
                 args.pop_back();
             }
         }
 
         return true;
     }
 
     /// Locate a subcommand by name with two conditions, should disabled subcommands be ignored, and should used
     /// subcommands be ignored
     App *_find_subcommand(const std::string &subc_name, bool ignore_disabled, bool ignore_used) const noexcept {
         for(const App_p &com : subcommands_) {
             if(com->disabled_ && ignore_disabled)
                 continue;
             if(com->get_name().empty()) {
                 auto subc = com->_find_subcommand(subc_name, ignore_disabled, ignore_used);
                 if(subc != nullptr) {
                     return subc;
                 }
             }
             if(com->check_name(subc_name)) {
                 if((!*com) || !ignore_used)
                     return com.get();
             }
         }
         return nullptr;
     }
 
     /// Parse a subcommand, modify args and continue
     ///
     /// Unlike the others, this one will always allow fallthrough
     /// return true if the subcommand was processed false otherwise
     bool _parse_subcommand(std::vector<std::string> &args) {
         if(_count_remaining_positionals(/* required */ true) > 0) {
             _parse_positional(args, false);
             return true;
         }
         auto com = _find_subcommand(args.back(), true, true);
         if(com != nullptr) {
             args.pop_back();
             if(!com->silent_) {
                 parsed_subcommands_.push_back(com);
             }
             com->_parse(args);
             auto parent_app = com->parent_;
             while(parent_app != this) {
                 parent_app->_trigger_pre_parse(args.size());
                 if(!com->silent_) {
                     parent_app->parsed_subcommands_.push_back(com);
                 }
                 parent_app = parent_app->parent_;
             }
             return true;
         }
 
         if(parent_ == nullptr)
             throw HorribleError("Subcommand " + args.back() + " missing");
         return false;
     }
 
     /// Parse a short (false) or long (true) argument, must be at the top of the list
     /// return true if the argument was processed or false if nothing was done
     bool _parse_arg(std::vector<std::string> &args, detail::Classifier current_type) {
 
         std::string current = args.back();
 
         std::string arg_name;
         std::string value;
         std::string rest;
 
         switch(current_type) {
         case detail::Classifier::LONG:
             if(!detail::split_long(current, arg_name, value))
                 throw HorribleError("Long parsed but missing (you should not see this):" + args.back());
             break;
         case detail::Classifier::SHORT:
             if(!detail::split_short(current, arg_name, rest))
                 throw HorribleError("Short parsed but missing! You should not see this");
             break;
         case detail::Classifier::WINDOWS_STYLE:
             if(!detail::split_windows_style(current, arg_name, value))
                 throw HorribleError("windows option parsed but missing! You should not see this");
             break;
         case detail::Classifier::SUBCOMMAND:
         case detail::Classifier::SUBCOMMAND_TERMINATOR:
         case detail::Classifier::POSITIONAL_MARK:
         case detail::Classifier::NONE:
         default:
             throw HorribleError("parsing got called with invalid option! You should not see this");
         }
 
         auto op_ptr =
             std::find_if(std::begin(options_), std::end(options_), [arg_name, current_type](const Option_p &opt) {
                 if(current_type == detail::Classifier::LONG)
                     return opt->check_lname(arg_name);
                 if(current_type == detail::Classifier::SHORT)
                     return opt->check_sname(arg_name);
                 // this will only get called for detail::Classifier::WINDOWS_STYLE
                 return opt->check_lname(arg_name) || opt->check_sname(arg_name);
             });
 
         // Option not found
         if(op_ptr == std::end(options_)) {
             for(auto &subc : subcommands_) {
                 if(subc->name_.empty() && !subc->disabled_) {
                     if(subc->_parse_arg(args, current_type)) {
                         if(!subc->pre_parse_called_) {
                             subc->_trigger_pre_parse(args.size());
                         }
                         return true;
                     }
                 }
             }
             // If a subcommand, try the master command
             if(parent_ != nullptr && fallthrough_)
                 return _get_fallthrough_parent()->_parse_arg(args, current_type);
             // don't capture missing if this is a nameless subcommand
             if(parent_ != nullptr && name_.empty()) {
                 return false;
             }
             // Otherwise, add to missing
             args.pop_back();
             _move_to_missing(current_type, current);
             return true;
         }
 
         args.pop_back();
 
         // Get a reference to the pointer to make syntax bearable
         Option_p &op = *op_ptr;
         /// if we require a separator add it here
         if(op->get_inject_separator()) {
             if(!op->results().empty() && !op->results().back().empty()) {
                 op->add_result(std::string{});
             }
         }
         int min_num = (std::min)(op->get_type_size_min(), op->get_items_expected_min());
         int max_num = op->get_items_expected_max();
         // check container like options to limit the argument size to a single type if the allow_extra_flags argument is
         // set. 16 is somewhat arbitrary (needs to be at least 4)
         if(max_num >= detail::expected_max_vector_size / 16 && !op->get_allow_extra_args()) {
             auto tmax = op->get_type_size_max();
             max_num = detail::checked_multiply(tmax, op->get_expected_min()) ? tmax : detail::expected_max_vector_size;
         }
         // Make sure we always eat the minimum for unlimited vectors
         int collected = 0;     // total number of arguments collected
         int result_count = 0;  // local variable for number of results in a single arg string
         // deal with purely flag like things
         if(max_num == 0) {
             auto res = op->get_flag_value(arg_name, value);
             op->add_result(res);
             parse_order_.push_back(op.get());
         } else if(!value.empty()) {  // --this=value
             op->add_result(value, result_count);
             parse_order_.push_back(op.get());
             collected += result_count;
             // -Trest
         } else if(!rest.empty()) {
             op->add_result(rest, result_count);
             parse_order_.push_back(op.get());
             rest = "";
             collected += result_count;
         }
 
         // gather the minimum number of arguments
         while(min_num > collected && !args.empty()) {
             std::string current_ = args.back();
             args.pop_back();
             op->add_result(current_, result_count);
             parse_order_.push_back(op.get());
             collected += result_count;
         }
 
         if(min_num > collected) {  // if we have run out of arguments and the minimum was not met
             throw ArgumentMismatch::TypedAtLeast(op->get_name(), min_num, op->get_type_name());
         }
 
         if(max_num > collected || op->get_allow_extra_args()) {  // we allow optional arguments
             auto remreqpos = _count_remaining_positionals(true);
             // we have met the minimum now optionally check up to the maximum
             while((collected < max_num || op->get_allow_extra_args()) && !args.empty() &&
                   _recognize(args.back(), false) == detail::Classifier::NONE) {
                 // If any required positionals remain, don't keep eating
                 if(remreqpos >= args.size()) {
                     break;
                 }
 
                 op->add_result(args.back(), result_count);
                 parse_order_.push_back(op.get());
                 args.pop_back();
                 collected += result_count;
             }
 
             // Allow -- to end an unlimited list and "eat" it
             if(!args.empty() && _recognize(args.back()) == detail::Classifier::POSITIONAL_MARK)
                 args.pop_back();
             // optional flag that didn't receive anything now get the default value
             if(min_num == 0 && max_num > 0 && collected == 0) {
                 auto res = op->get_flag_value(arg_name, std::string{});
                 op->add_result(res);
                 parse_order_.push_back(op.get());
             }
         }
 
         // if we only partially completed a type then add an empty string for later processing
         if(min_num > 0 && op->get_type_size_max() != min_num && (collected % op->get_type_size_max()) != 0) {
             op->add_result(std::string{});
         }
 
         if(!rest.empty()) {
             rest = "-" + rest;
             args.push_back(rest);
         }
         return true;
     }
 
     /// Trigger the pre_parse callback if needed
     void _trigger_pre_parse(std::size_t remaining_args) {
         if(!pre_parse_called_) {
             pre_parse_called_ = true;
             if(pre_parse_callback_) {
                 pre_parse_callback_(remaining_args);
             }
         } else if(immediate_callback_) {
             if(!name_.empty()) {
                 auto pcnt = parsed_;
                 auto extras = std::move(missing_);
                 clear();
                 parsed_ = pcnt;
                 pre_parse_called_ = true;
                 missing_ = std::move(extras);
             }
         }
     }
 
     /// Get the appropriate parent to fallthrough to which is the first one that has a name or the main app
     App *_get_fallthrough_parent() {
         if(parent_ == nullptr) {
             throw(HorribleError("No Valid parent"));
         }
         auto fallthrough_parent = parent_;
         while((fallthrough_parent->parent_ != nullptr) && (fallthrough_parent->get_name().empty())) {
             fallthrough_parent = fallthrough_parent->parent_;
         }
         return fallthrough_parent;
     }
 
     /// Helper function to run through all possible comparisons of subcommand names to check there is no overlap
     const std::string &_compare_subcommand_names(const App &subcom, const App &base) const {
         static const std::string estring;
         if(subcom.disabled_) {
             return estring;
         }
         for(auto &subc : base.subcommands_) {
             if(subc.get() != &subcom) {
                 if(subc->disabled_) {
                     continue;
                 }
                 if(!subcom.get_name().empty()) {
                     if(subc->check_name(subcom.get_name())) {
                         return subcom.get_name();
                     }
                 }
                 if(!subc->get_name().empty()) {
                     if(subcom.check_name(subc->get_name())) {
                         return subc->get_name();
                     }
                 }
                 for(const auto &les : subcom.aliases_) {
                     if(subc->check_name(les)) {
                         return les;
                     }
                 }
                 // this loop is needed in case of ignore_underscore or ignore_case on one but not the other
                 for(const auto &les : subc->aliases_) {
                     if(subcom.check_name(les)) {
                         return les;
                     }
                 }
                 // if the subcommand is an option group we need to check deeper
                 if(subc->get_name().empty()) {
                     auto &cmpres = _compare_subcommand_names(subcom, *subc);
                     if(!cmpres.empty()) {
                         return cmpres;
                     }
                 }
                 // if the test subcommand is an option group we need to check deeper
                 if(subcom.get_name().empty()) {
                     auto &cmpres = _compare_subcommand_names(*subc, subcom);
                     if(!cmpres.empty()) {
                         return cmpres;
                     }
                 }
             }
         }
         return estring;
     }
     /// Helper function to place extra values in the most appropriate position
     void _move_to_missing(detail::Classifier val_type, const std::string &val) {
         if(allow_extras_ || subcommands_.empty()) {
             missing_.emplace_back(val_type, val);
             return;
         }
         // allow extra arguments to be places in an option group if it is allowed there
         for(auto &subc : subcommands_) {
             if(subc->name_.empty() && subc->allow_extras_) {
                 subc->missing_.emplace_back(val_type, val);
                 return;
             }
         }
         // if we haven't found any place to put them yet put them in missing
         missing_.emplace_back(val_type, val);
     }
 
   public:
     /// function that could be used by subclasses of App to shift options around into subcommands
     void _move_option(Option *opt, App *app) {
         if(opt == nullptr) {
             throw OptionNotFound("the option is NULL");
         }
         // verify that the give app is actually a subcommand
         bool found = false;
         for(auto &subc : subcommands_) {
             if(app == subc.get()) {
                 found = true;
             }
         }
         if(!found) {
             throw OptionNotFound("The Given app is not a subcommand");
         }
 
         if((help_ptr_ == opt) || (help_all_ptr_ == opt))
             throw OptionAlreadyAdded("cannot move help options");
 
         if(config_ptr_ == opt)
             throw OptionAlreadyAdded("cannot move config file options");
 
         auto iterator =
             std::find_if(std::begin(options_), std::end(options_), [opt](const Option_p &v) { return v.get() == opt; });
         if(iterator != std::end(options_)) {
             const auto &opt_p = *iterator;
             if(std::find_if(std::begin(app->options_), std::end(app->options_), [&opt_p](const Option_p &v) {
                    return (*v == *opt_p);
                }) == std::end(app->options_)) {
                 // only erase after the insertion was successful
                 app->options_.push_back(std::move(*iterator));
                 options_.erase(iterator);
             } else {
                 throw OptionAlreadyAdded("option was not located: " + opt->get_name());
             }
         } else {
             throw OptionNotFound("could not locate the given Option");
         }
     }
 };  // namespace CLI
 
 /// Extension of App to better manage groups of options
 class Option_group : public App {
   public:
     Option_group(std::string group_description, std::string group_name, App *parent)
         : App(std::move(group_description), "", parent) {
         group(group_name);
         // option groups should have automatic fallthrough
     }
     using App::add_option;
     /// Add an existing option to the Option_group
     Option *add_option(Option *opt) {
         if(get_parent() == nullptr) {
             throw OptionNotFound("Unable to locate the specified option");
         }
         get_parent()->_move_option(opt, this);
         return opt;
     }
     /// Add an existing option to the Option_group
     void add_options(Option *opt) { add_option(opt); }
     /// Add a bunch of options to the group
     template <typename... Args> void add_options(Option *opt, Args... args) {
         add_option(opt);
         add_options(args...);
     }
     using App::add_subcommand;
     /// Add an existing subcommand to be a member of an option_group
     App *add_subcommand(App *subcom) {
         App_p subc = subcom->get_parent()->get_subcommand_ptr(subcom);
         subc->get_parent()->remove_subcommand(subcom);
         add_subcommand(std::move(subc));
         return subcom;
     }
 };
 /// Helper function to enable one option group/subcommand when another is used
 inline void TriggerOn(App *trigger_app, App *app_to_enable) {
     app_to_enable->enabled_by_default(false);
     app_to_enable->disabled_by_default();
     trigger_app->preparse_callback([app_to_enable](std::size_t) { app_to_enable->disabled(false); });
 }
 
 /// Helper function to enable one option group/subcommand when another is used
 inline void TriggerOn(App *trigger_app, std::vector<App *> apps_to_enable) {
     for(auto &app : apps_to_enable) {
         app->enabled_by_default(false);
         app->disabled_by_default();
     }
 
     trigger_app->preparse_callback([apps_to_enable](std::size_t) {
         for(auto &app : apps_to_enable) {
             app->disabled(false);
         }
     });
 }
 
 /// Helper function to disable one option group/subcommand when another is used
 inline void TriggerOff(App *trigger_app, App *app_to_enable) {
     app_to_enable->disabled_by_default(false);
     app_to_enable->enabled_by_default();
     trigger_app->preparse_callback([app_to_enable](std::size_t) { app_to_enable->disabled(); });
 }
 
 /// Helper function to disable one option group/subcommand when another is used
 inline void TriggerOff(App *trigger_app, std::vector<App *> apps_to_enable) {
     for(auto &app : apps_to_enable) {
         app->disabled_by_default(false);
         app->enabled_by_default();
     }
 
     trigger_app->preparse_callback([apps_to_enable](std::size_t) {
         for(auto &app : apps_to_enable) {
             app->disabled();
         }
     });
 }
 
 /// Helper function to mark an option as deprecated
 inline void deprecate_option(Option *opt, const std::string &replacement = "") {
     Validator deprecate_warning{[opt, replacement](std::string &) {
                                     std::cout << opt->get_name() << " is deprecated please use '" << replacement
                                               << "' instead\n";
                                     return std::string();
                                 },
                                 "DEPRECATED"};
     deprecate_warning.application_index(0);
     opt->check(deprecate_warning);
     if(!replacement.empty()) {
         opt->description(opt->get_description() + " DEPRECATED: please use '" + replacement + "' instead");
     }
 }
 
 /// Helper function to mark an option as deprecated
 inline void deprecate_option(App *app, const std::string &option_name, const std::string &replacement = "") {
     auto opt = app->get_option(option_name);
     deprecate_option(opt, replacement);
 }
 
 /// Helper function to mark an option as deprecated
 inline void deprecate_option(App &app, const std::string &option_name, const std::string &replacement = "") {
     auto opt = app.get_option(option_name);
     deprecate_option(opt, replacement);
 }
 
 /// Helper function to mark an option as retired
 inline void retire_option(App *app, Option *opt) {
     App temp;
     auto option_copy = temp.add_option(opt->get_name(false, true))
                            ->type_size(opt->get_type_size_min(), opt->get_type_size_max())
                            ->expected(opt->get_expected_min(), opt->get_expected_max())
                            ->allow_extra_args(opt->get_allow_extra_args());
 
     app->remove_option(opt);
     auto opt2 = app->add_option(option_copy->get_name(false, true), "option has been retired and has no effect")
                     ->type_name("RETIRED")
                     ->default_str("RETIRED")
                     ->type_size(option_copy->get_type_size_min(), option_copy->get_type_size_max())
                     ->expected(option_copy->get_expected_min(), option_copy->get_expected_max())
                     ->allow_extra_args(option_copy->get_allow_extra_args());
 
     Validator retired_warning{[opt2](std::string &) {
                                   std::cout << "WARNING " << opt2->get_name() << " is retired and has no effect\n";
                                   return std::string();
                               },
                               ""};
     retired_warning.application_index(0);
     opt2->check(retired_warning);
 }
 
 /// Helper function to mark an option as retired
 inline void retire_option(App &app, Option *opt) { retire_option(&app, opt); }
 
 /// Helper function to mark an option as retired
 inline void retire_option(App *app, const std::string &option_name) {
 
     auto opt = app->get_option_no_throw(option_name);
     if(opt != nullptr) {
         retire_option(app, opt);
         return;
     }
     auto opt2 = app->add_option(option_name, "option has been retired and has no effect")
                     ->type_name("RETIRED")
                     ->expected(0, 1)
                     ->default_str("RETIRED");
     Validator retired_warning{[opt2](std::string &) {
                                   std::cout << "WARNING " << opt2->get_name() << " is retired and has no effect\n";
                                   return std::string();
                               },
                               ""};
     retired_warning.application_index(0);
     opt2->check(retired_warning);
 }
 
 /// Helper function to mark an option as retired
 inline void retire_option(App &app, const std::string &option_name) { retire_option(&app, option_name); }
 
 namespace FailureMessage {
 
 /// Printout a clean, simple message on error (the default in CLI11 1.5+)
 inline std::string simple(const App *app, const Error &e) {
     std::string header = std::string(e.what()) + "\n";
     std::vector<std::string> names;
 
     // Collect names
     if(app->get_help_ptr() != nullptr)
         names.push_back(app->get_help_ptr()->get_name());
 
     if(app->get_help_all_ptr() != nullptr)
         names.push_back(app->get_help_all_ptr()->get_name());
 
     // If any names found, suggest those
     if(!names.empty())
         header += "Run with " + detail::join(names, " or ") + " for more information.\n";
 
     return header;
 }
 
 /// Printout the full help string on error (if this fn is set, the old default for CLI11)
 inline std::string help(const App *app, const Error &e) {
     std::string header = std::string("ERROR: ") + e.get_name() + ": " + e.what() + "\n";
     header += app->help();
     return header;
 }
 
 }  // namespace FailureMessage
 
 namespace detail {
 /// This class is simply to allow tests access to App's protected functions
 struct AppFriend {
 #ifdef CLI11_CPP14
 
     /// Wrap _parse_short, perfectly forward arguments and return
     template <typename... Args> static decltype(auto) parse_arg(App *app, Args &&... args) {
         return app->_parse_arg(std::forward<Args>(args)...);
     }
 
     /// Wrap _parse_subcommand, perfectly forward arguments and return
     template <typename... Args> static decltype(auto) parse_subcommand(App *app, Args &&... args) {
         return app->_parse_subcommand(std::forward<Args>(args)...);
     }
 #else
     /// Wrap _parse_short, perfectly forward arguments and return
     template <typename... Args>
     static auto parse_arg(App *app, Args &&... args) ->
         typename std::result_of<decltype (&App::_parse_arg)(App, Args...)>::type {
         return app->_parse_arg(std::forward<Args>(args)...);
     }
 
     /// Wrap _parse_subcommand, perfectly forward arguments and return
     template <typename... Args>
     static auto parse_subcommand(App *app, Args &&... args) ->
         typename std::result_of<decltype (&App::_parse_subcommand)(App, Args...)>::type {
         return app->_parse_subcommand(std::forward<Args>(args)...);
     }
 #endif
     /// Wrap the fallthrough parent function to make sure that is working correctly
     static App *get_fallthrough_parent(App *app) { return app->_get_fallthrough_parent(); }
 };
 }  // namespace detail
 
 // [CLI11:app_hpp:end]
 }  // namespace CLI