Returns the reference of a non-empty argument.
Checks whether the given argument is a named argument with the specified name.
Checks whether the given argument is an empty argument.
Checks whether the given argument is a named argument.
Checks whether the given argument is not an empty argument.
Checks whether the given argument is a positional argument.
Checks whether the given argument is an unnamed argument (either positional or empty).
EmptyArgument - the marker for empty arguments
Helper functions to work with FunctionArguments.