Get a random code of country.

        Default format is :attr:`~enums.CountryCode.A2` (ISO 3166-1-alpha2),
        you can change it by passing parameter ``fmt`` with enum object
        :class:`~enums.CountryCode`.

        :param fmt: Enum object CountryCode.
        :return: Country code in selected format.
        :raises KeyError: if fmt is not supported.

def country_code(self, fmt: Optional[CountryCode] = CountryCode.A2) -> str:
        """Get a random code of country.

        Default format is :attr:`~enums.CountryCode.A2` (ISO 3166-1-alpha2),
        you can change it by passing parameter ``fmt`` with enum object
        :class:`~enums.CountryCode`.

        :param fmt: Enum object CountryCode.
        :return: Country code in selected format.
        :raises KeyError: if fmt is not supported.
        """
        key = self._validate_enum(fmt, CountryCode)
        return self.random.choice(COUNTRY_CODES[key])