Return the last_updated time of the current request item

        :return: A DateTime object
        :rettype: datetetime.datetime

def last_updated(self):
        '''Return the last_updated time of the current request item

        :return: A DateTime object
        :rettype: datetetime.datetime
        '''

        key = self.get_key_from_request()
        max_age = self.get_max_age()

        if max_age == 0:
            return datetime.fromtimestamp(Storage.start_time)

        ttl = self.get_storage().ttl(key)

        if ttl >= 0:
            return datetime.now() - timedelta(
                seconds=(
                    max_age - ttl
                )
            )

        if ttl == -1:
            # Per Redis docs: -1 is no expiry, -2 is does not exists.
            return datetime.fromtimestamp(Storage.start_time)

        # Should never reach here. It means the storage put failed or the item
        # somehow does not exists anymore.
        return datetime.now()