def get_user(self, user_id):

        user = self._users.get(user_id, None)
        if not user:
            user = keystone.user_get(self._request, user_id)
            # caching the user, for later use
            self._users[user_id] = user
        return user
Returns user fetched form API
dataset/ETHPy150Open Havate/havate-openstack/proto-build/gui/horizon/Horizon_GUI/openstack_dashboard/api/ceilometer.py/CeilometerUsage.get_user