def save(self, expected_value=None, return_values=None):
        return self.table.layer2.update_item(self, expected_value,
                                             return_values)
If the given credentials are valid, return a User object.
dataset/ETHPy150Open yyuu/botornado/boto/dynamodb/item.py/Item.save--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.2/django/contrib/auth/__init__.py/authenticate