https://hachyderm.io/@Mara/111357549294998960 gave me a good chuckle.

It also reminded me of a thing that I never really considered until I started contributing to #GopherJS: a += b and a = a + b are not semantically equivalent statements. In the former a is evaluated only once, and in the latter twice. That doesn't matter when a is just a variable, but if it includes a function call with side effects the double evaluation may cause all sorts of havoc.