v2.py

    async def verify(self, token):
        """
        Return token data for *token*.
        """
        cc = await self.pool.cursor()
        try:
            c = cc.__enter__()
            await c.execute(
                "SELECT user_id, created, purpose FROM tokens "
                "WHERE token=%s AND system=%s AND valid=true",
                (token, self.system,)
            )
            rv = await c.fetchone()
        except Exception as e:
            await self.pool.clear()
            raise StorageError(e)
        finally:
            cc.__exit__()

        if rv is None:
            raise InvalidToken

        return TokenData(
            token=token,
            system=self.system,
            user_id=rv[0],
            created=rv[1],
            purpose=rv[2],
        )