Nobody has mentioned it, but in this sort of language, you're chaining expressions onto the right-hand side. Putting commas on the left-hand side means they're

Nobody has mentioned it, but in this sort of language, you're chaining expressions onto the right-hand side. Putting commas on the left-hand side means they're out of your way once and for all. The versioning diff argument is much less interesting. Most people don't care about that.