docs: def get_grade_systems_by_gradebooks(self, gradebook_ids):
          """Gets the list of grade systems corresponding to a list of ``Gradebooks``.
  
          arg:    gradebook_ids (osid.id.IdList): list of gradebook
                  ``Ids``
          return: (osid.grading.GradeSystemList) - list of grade systems
          raise:  NullArgument - ``gradebook_ids`` is ``null``
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method must be implemented.*
  
          """
          # Implemented from template for
          # osid.resource.ResourceBinSession.get_resources_by_bins
          grade_system_list = []
          for gradebook_id in gradebook_ids:
              grade_system_list += list(
                  self.get_grade_systems_by_gradebook(gradebook_id))
          return objects.GradeSystemList(grade_system_list)