@utilities.remove_null_proxy_kwarg<EOL><INDENT>def get_gradebook_column_gradebook_assignment_session(self):<DEDENT>
if not self.supports_gradebook_column_gradebook_assignment():<EOL><INDENT>raise errors.Unimplemented()<EOL><DEDENT>return sessions.GradebookColumnGradebookAssignmentSession(runtime=self._runtime)<EOL>
Gets the session for assigning gradebook column to gradebook mappings.

        return: (osid.grading.GradebookColumnGradebookAssignmentSession)
                - a ``GradebookColumnGradebookAssignmentSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented -
                ``supports_gradebook_column_gradebook_assignment()`` is
                ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_gradebook_column_gradebook_assignment()`` is
        ``true``.*