Returns: generator of all groups in this country

def groups(self) -> typing.Iterator['Group']:
        """
        Returns: generator of all groups in this country
        """
        for group_category in Mission.valid_group_categories:
            if group_category in self._section_this_country.keys():
                for group_index in self._section_this_country[group_category]['group']:
                    if group_index not in self.__groups[group_category]:
                        self.__groups[group_category][group_index] = Group(self.d, self.l10n, self.coa_color,
                                                                           self.country_index, group_category,
                                                                           group_index)
                    yield self.__groups[group_category][group_index]