Ah, yeah I see; there's an ambiguity in parsing expressions and tuples which could lead to subtle typing bugs. There's another ambiguity that (a for a in b) is

Ah, yeah I see; there's an ambiguity in parsing expressions and tuples which could lead to subtle typing bugs. There's another ambiguity that (a for a in b) is not a tuple, but a generator, while [a for a in b] is a list.