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