def txn_useNonce(self, server_url, timestamp, salt):
        if abs(timestamp - time.time()) > nonce.SKEW:
            return False

        try:
            self.db_add_nonce(server_url, timestamp, salt)
        except self.exceptions.IntegrityError:
            # The key uniqueness check failed
            return False
        else:
            # The nonce was successfully added
            return True
Return whether this nonce is present, and if it is, then
dataset/ETHPy150Open CollabQ/CollabQ/openid/store/sqlstore.py/SQLStore.txn_useNonce