def get_level_id(self):
<EOL>if not bool(self._my_map['<STR_LIT>']):<EOL><INDENT>raise errors.IllegalState('<STR_LIT>')<EOL><DEDENT>else:<EOL><INDENT>return Id(self._my_map['<STR_LIT>'])<EOL><DEDENT>
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.*