code: def get_based_on_grades_metadata(self):
          
          # Implemented from template for osid.resource.ResourceForm.get_group_metadata_template
          metadata = dict(self._mdata['based_on_grades'])
          metadata.update({'existing_boolean_values': self._my_map['basedOnGrades']})
          return Metadata(**metadata)
docs: Gets the metadata for a grade-based designation.
  
          return: (osid.Metadata) - metadata for the grade-based
                  designation
          *compliance: mandatory -- This method must be implemented.*