def METHOD_NAME(dir_path):
    """
    Returns True iff dir_path is a valid rule directory which exists
    To be valid, dir_path must exist and be a directory and the file
    returned by get_rule_dir_yaml(dir_path) must exist.
    """
    rule_yaml = get_rule_dir_yaml(dir_path)
    is_dir = os.path.isdir(dir_path)
    has_rule_yaml = os.path.exists(rule_yaml)
    return is_dir and has_rule_yaml