[Tarean]

Actually, the code "branches" four times.

Three times you introduce possible failure, the original parse as well as each call to flatMap. It flattens each of these possible failures into one, though, so you don't have to think about it!

So if the programmer is sane and doesn't hide side effects in there you only have to think about branching at the pattern match - if any step failed do this, otherwise do this!