@classmethod
def cmd_name(cls):
    """convert child class' __module__ to name of argparse command"""
    name_str = cls.__module__.rsplit('.', 1)[-1]
    if not name_str.endswith(cls._module_postfix):
        raise ImportError(
            f'{name_str} module name must end with "{cls._module_postfix}".')
    return name_str[:-len(cls._module_postfix)]
