docs: def get_level_id(self):
          """Gets the ``Id`` of a ``Grade`` corresponding to the assessment difficulty.
  
          return: (osid.id.Id) - a grade ``Id``
          *compliance: mandatory -- This method must be implemented.*
  
          """
          # Implemented from template for osid.resource.Resource.get_avatar_id_template
          if not bool(self._my_map['levelId']):
              raise errors.IllegalState('this Assessment has no level')
          else:
              return Id(self._my_map['levelId'])