@staticmethod
def compose_locale(language_code, country_code=None):
    """
        Return the string representation of the locale specified with a ISO
        639-3 alpha-3 code (or alpha-2 code), optionally followed by a dash
        character `-` and a ISO 3166-1 alpha-2 code.


        :param language_code: a ISO 639-3 alpha-3 code (or alpha-2 code).

        :param country_code: a ISO 3166-1 alpha-2 code.


        :return: a string representing a locale.
        """
    return (language_code if country_code is None else
        f'{language_code}-{country_code}')
