code: def groups(self) -> typing.Iterator['Group']:
          
          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]
docs: Returns: generator of all groups in this country