def METHOD_NAME(decorator):  # pragma: no cover
    """Make function callable.
    See https://stackoverflow.com/questions/3888158/making-decorators-with-
    optional-arguments
    """
    @wraps(decorator)
    def inner(*args, **kw):  # pragma: no cover
        if len(args) == 1 and not kw and callable(args[0]):
            return decorator()(args[0])
        else:
            return decorator(*args, **kw)
    return inner