def set_number(self, key, value):
        """ set a key's value
        """
        storage = self.storage

        if not isinstance(value, int):
            logger.error("set_number: Value must be an integer")
            return

        try:
            lock.acquire()
            storage[key] = value
        finally:
            self.storage._p_changed = True
            lock.release()

        return storage[key]
set a key's value