These definitions were written by [Martin Poelstra](https://github.com/poelstra), [Mizunashi Mana](https://github.com/mizunashi-mana), [Jeffery Grajkowski](https://github.com/pushplay), [Jimi (Dimitris) Charalampidis](https://github.com/JimiC), [Steffen Viken Valvåg](https://github.com/steffenvv), [Emily Marigold Klassen](https://github.com/forivall), [ExE Boss](https://github.com/ExE-Boss), and [Aankhen](https://github.com/Aankhen).
* Provide a synchronous function to coerce or transform the value(s) given on the command line for `key`.
*
* The coercion function should accept one argument, representing the parsed value from the command line, and should return a new value or throw an error.
* The returned value will be used as the value for `key` (or one of its aliases) in `argv`.
*
* If the function throws, the error will be treated as a validation failure, delegating to either a custom `.fail()` handler or printing the error message in the console.
*
* Coercion will be applied to a value after all other modifications, such as `.normalize()`.
*
* Optionally `.coerce()` can take an object that maps several keys to their respective coercion function.
*
* You can also map the same function to several keys at one time. Just pass an array of keys as the first argument to `.coerce()`.
*
* If you are using dot-notion or arrays, .e.g., `user.email` and `user.password`, coercion will be applied to the final object that has been parsed
* Enable bash/zsh-completion shortcuts for commands and options.
*
* If invoked without parameters, `.completion()` will make completion the command to output the completion script.
*
* @param [cmd] When present in `argv._`, will result in the `.bashrc` or `.zshrc` completion script being outputted.
* To enable bash/zsh completions, concat the generated script to your `.bashrc` or `.bash_profile` (or `.zshrc` for zsh).
* @param [description] Provide a description in your usage instructions for the command that generates the completion scripts.
* @param [func] Rather than relying on yargs' default completion functionality, which shiver me timbers is pretty awesome, you can provide your own completion method.
* Interpret `key` as a boolean flag, but set its parsed value to the number of flag occurrences rather than `true` or `false`. Default value is thus `0`.
* You can demand a minimum and a maximum number a user can have within your program, as well as provide corresponding error messages if either of the demands is not met.
/** Should yargs attempt to detect the os' locale? Defaults to `true`. */
detectLocale(detect:boolean):Argv<T>;
/**
* Tell yargs to parse environment variables matching the given prefix and apply them to argv as though they were command line arguments.
*
* Use the "__" separator in the environment variable to indicate nested options. (e.g. prefix_nested__foo => nested.foo)
*
* If this method is called with no argument or with an empty string or with true, then all env vars will be applied to argv.
*
* Program arguments are defined in this order of precedence:
* 1. Command line args
* 2. Env vars
* 3. Config file/objects
* 4. Configured defaults
*
* Env var parsing is disabled by default, but you can also explicitly disable it by calling `.env(false)`, e.g. if you need to undo previous configuration.
*/
env():Argv<T>;
env(prefix:string):Argv<T>;
env(enable:boolean):Argv<T>;
/** A message to print at the end of the usage instructions */
epilog(msg:string):Argv<T>;
/** A message to print at the end of the usage instructions */
epilogue(msg:string):Argv<T>;
/**
* Give some example invocations of your program.
* Inside `cmd`, the string `$0` will get interpolated to the current script name or node command for the present script similar to how `$0` works in bash or perl.
* Examples will be printed out as part of the help message.
/** Manually indicate that the program should exit, and provide context about why we wanted to exit. Follows the behavior set by `.exitProcess().` */
exit(code:number,err:Error):void;
/**
* By default, yargs exits the process when the user passes a help flag, the user uses the `.version` functionality, validation fails, or the command handler fails.
* Calling `.exitProcess(false)` disables this behavior, enabling further actions after yargs have been validated.
*/
exitProcess(enabled:boolean):Argv<T>;
/**
* Method to execute when a failure occurs, rather than printing the failure message.
* @param func Is called with the failure message that would have been printed, the Error instance originally thrown and yargs state when the failure occurred.
* Given the key `x` is set, it is required that the key `y` is set.
* y` can either be the name of an argument to imply, a number indicating the position of an argument or an array of multiple implications to associate with `x`.
*
* Optionally `.implies()` can accept an object specifying multiple implications.
* Return the locale that yargs is currently using.
*
* By default, yargs will auto-detect the operating system's locale so that yargs-generated help content will display in the user's language.
*/
locale():string;
/**
* Override the auto-detected locale from the user's operating system with a static locale.
* Note that the OS locale can be modified by setting/exporting the `LC_ALL` environment variable.
*/
locale(loc:string):Argv<T>;
/**
* Define global middleware functions to be called first, in list order, for all cli command.
* @param callbacks Can be a function or a list of functions. Each callback gets passed a reference to argv.
* @param [applyBeforeValidation] Set to `true` to apply middleware before validation. This will execute the middleware prior to validation checks, but after parsing.
* Allows you to configure a command's positional arguments with an API similar to `.option()`.
* `.positional()` should be called in a command's builder function, and is not available on the top-level yargs instance. If so, it will throw an error.
* Override the default strings used by yargs with the key/value pairs provided in obj
*
* If you explicitly specify a locale(), you should do so before calling `updateStrings()`.
*/
updateStrings(obj:{[key:string]:string}):Argv<T>;
/**
* Set a usage message to show which commands to use.
* Inside `message`, the string `$0` will get interpolated to the current script name or node command for the present script similar to how `$0` works in bash or perl.
*
* If the optional `description`/`builder`/`handler` are provided, `.usage()` acts an an alias for `.command()`.
* This allows you to use `.usage()` to configure the default command that will be run as an entry-point to your application
* and allows you to provide configuration for the positional arguments accepted by your program:
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