An experienced developer I know with a dead simple function fell for the classic 10+20+30=102030 bug the other day. Had it not been noticed in production it wou

An experienced developer I know with a dead simple function fell for the classic 10+20+30=102030 bug the other day. Had it not been noticed in production it would have been very costly. It was an edge case he had not encountered in the wild, but had thought to handle just-in-case. Integration tests missed it too. Sure, good unit tests could have caught it, but Typescript would not have allowed it in the first place.