code: def get_gradebook_column_id(self):
          
          # Implemented from template for osid.learning.Activity.get_objective_id
          if not bool(self._my_map['gradebookColumnId']):
              raise errors.IllegalState('gradebook_column empty')
          return Id(self._my_map['gradebookColumnId'])
docs: Gets the ``Id`` of the ``GradebookColumn``.
  
          return: (osid.id.Id) - the ``Id`` of the ``GradebookColumn``
          *compliance: mandatory -- This method must be implemented.*