MakeFixedCommand wraps a function which accepts either [ExecuteType] or, [ExecuteType] and variadic string parameters, which are passed to `executeFn` during [command.Execute].

MakeNiladicCommand returns a command that wraps `executeFn`.

MakeVariadicCommand wraps a function which accepts either variaic [ExecuteType] or, a slice of string parameters and variadic [ExecuteType] which are passed to `executeFn` during [command.Execute].

SubcommandGroup returns a command that only defers to subcommands.

WithSubcommands provides a command with subcommands.

WithUsageOutput sets the writer that is written to when [Command.Execute] receives a request for help, or returns [UsageError].