How can I return a tuple of arrays from a proc. Having difficulty with proc signature

[xigoi]

I'd intuitively expect `tuple[int, int]` to be the correct syntax because 
that's how specialization of generic types is written in Nim, whereas `(int, 
int)` should be a tuple of types (which is not the same thing as a tuple type). 
And then if `(int, int)` works, why does `(x: int, y: int)` not work?