code: def get_objective_bank_ids_by_activity(self, activity_id):
          
          # Implemented from template for
          # osid.resource.ResourceBinSession.get_bin_ids_by_resource
          mgr = self._get_provider_manager('LEARNING', local=True)
          lookup_session = mgr.get_activity_lookup_session(proxy=self._proxy)
          lookup_session.use_federated_objective_bank_view()
          activity = lookup_session.get_activity(activity_id)
          id_list = []
          for idstr in activity._my_map['assignedObjectiveBankIds']:
              id_list.append(Id(idstr))
          return IdList(id_list)
docs: Gets the list of ``ObjectiveBank Ids`` mapped to a ``Activity``.
  
          arg:    activity_id (osid.id.Id): ``Id`` of a ``Activity``
          return: (osid.id.IdList) - list of objective bank ``Ids``
          raise:  NotFound - ``activity_id`` is not found
          raise:  NullArgument - ``activity_id`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method must be implemented.*