code: def get_group(self, group_id):
          
          response = self._do_request(
              'GET', '/v2/groups/{group_id}'.format(group_id=group_id))
          return self._parse_response(response, MarathonGroup)
docs: Get a single group.
  
          :param str group_id: group ID
  
          :returns: group
          :rtype: :class:`marathon.models.group.MarathonGroup`