code: def get_group(self, group_name):
          
          response = self.client.get_group(GroupName=group_name,
                                           UserPoolId=self.user_pool_id)
          return self.get_group_obj(response.get('Group'))
docs: Get a group by a name
          :param group_name: name of a group
          :return: instance of the self.group_class