That's really geeky, but according to his check-ins, Roselli spent Friday night having dessert with a woman and Saturday morning on a charity bike ride.
And if candidate nodes already have hashcash installed (but not some custom software tool), answering a hashcash challenge can act as a sort of "you must be this tall to enter this ride" style check.
如果参与节点已经安装了hashcash(而不是一些定制的软件工具)，那么，对hashcash质询的回答就可以作为一种“必须达到某种高度才能登堂入室(you must be this tall to enter this ride)”风格的校验。