在硬件构建的场景里，需求即入口，入口即支付。这种“零距离”的转化效率，是任何云端API调用或软件订阅模式都无法比拟的，对于拥有成熟交易生态的玩家，硬件可以说是将流量直接“泵入”营收的终极阀门。
Ok, but you still don’t want to have to change your API to add this，更多细节参见同城约会
* Write a detailed test suite as you add more features. The test must be re-executed at every major change.。同城约会对此有专业解读
async *transform(source) {