Gets a country from its name

        Args:
            country_id: country id

        Returns: Country

def get_country_by_id(self, country_id: int) -> typing.Optional['Country']:
        """
        Gets a country from its name

        Args:
            country_id: country id

        Returns: Country
        """
        VALID_POSITIVE_INT.validate(country_id, 'get_country_by_id')
        if country_id not in self._countries_by_id.keys():
            for country in self.countries:

                if country.country_id == country_id:
                    self._countries_by_id[country_id] = country
                    return country
            raise ValueError(country_id)
        else:
            return self._countries_by_id[country_id]