@classmethod
def namespace(cls):
    """Return namespace corresponding to self.ARGUMENT

        ARGUMENT is a command line argument, thus something in the style of `--code-change-type`.
        When arguments are passed they are saved in namespace in the style of `code_change_type`.
        This property converts command-line style to namespace style.
        """
    if not cls.ARGUMENT:
        return None
    return cls.ARGUMENT.lstrip('-').replace('-', '_')
