docs: def local_manager_gid(self):
          """Group id of local manager group of current authenticated member.
  
          Currently a user can be assigned only to one local manager group. If
          more than one local manager group is configured, an error is raised.
          """
          config = self.root['settings']['ugm_localmanager'].attrs
          user = security.authenticated_user(get_current_request())
          if not user:
              return None
          gids = user.group_ids
          adm_gids = list()
          for gid in gids:
              rule = config.get(gid)
              if rule:
                  adm_gids.append(gid)
          if len(adm_gids) == 0:
              return None
          if len(adm_gids) > 1:
              msg = (u"Authenticated member defined in local manager "
                     u"groups %s but only one management group allowed for "
                     u"each user. Please contact System Administrator in "
                     u"order to fix this problem.")
              exc = msg % ', '.join(["'%s'" % gid for gid in adm_gids])
              raise Exception(exc)
          return adm_gids[0]