def select_for_update(self, **kwargs):
        # Default to false for nowait
        nowait = kwargs.pop('nowait', False)
        obj = self._clone()
        obj.query.select_for_update = True
        obj.query.select_for_update_nowait = nowait
        return obj
Returns a new QuerySet instance that will select objects with a
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/db/models/query.py/QuerySet.select_for_update