@utilities.arguments_not_none<EOL><INDENT>def get_items_by_answer(self, answer_id):<DEDENT>
raise errors.Unimplemented()<EOL>
Gets an ``ItemList`` containing the given answer.

        In plenary mode, the returned list contains all known items or
        an error results. Otherwise, the returned list may contain only
        those assessment items that are accessible through this session.

        arg:    answer_id (osid.id.Id): an answer ``Id``
        return: (osid.assessment.ItemList) - the returned ``Item`` list
        raise:  NullArgument - ``answer_id`` is ``null``
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure occurred
        *compliance: mandatory -- This method must be implemented.*