def _compare_keys(self, left, right):

        return cmp(''.join(left[0][1:]), ''.join(right[0][1:]))
:param sys_module: A ``sys`` like object whose ``argv``, ``stdout`` and
dataset/ETHPy150Open googlei18n/nototools/nototools/gpos_diff.py/GposDiffFinder._compare_keys--crossover with--dataset/ETHPy150Open ClusterHQ/flocker/admin/packaging.py/DockerBuildScript.__init__