let a;
let a: () = ();
let (mut a, ref b) = (i32, &i32);
let (mut a, ref b): (i32, &i32);
let a = [1,2,3];
let `let` a = 1
let (mut a, b): (u32, u32) = [1, 2];
let (mut a, b) = (1, 2, 3);
let (mut a, b) = [1, 2]
let (mut a, b) = (1, 2)
let case Fraction(mut a, b) = Fraction(1 ,2)