def new_child(self):                        # like Django's Context.push()
            'New ChainMap with a new dict followed by all previous maps.'
            return self.__class__({}, *self.maps)
New ChainMap with a new dict followed by all previous maps.
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_vendor/distlib/compat.py