[mcav]

That's silly. All of the methods are side-effect-free. It'd be useless and confusing to suffix some methods and not others.

[thatswrong0]

Not to mention that if you see the assignment, you know that it's returning something, so you wouldn't (shouldn't) assume that the method is necessarily mutating the object. Plus I like the idea of moving towards immutable by default and calling methods that by name are explicit about mutation.