ref: eff0ab25c1d542934e1a5d9df45da403777dd3c6
dir: /lib/iter/test/enum.myr/
use std use iter const main = { var n n = 0 for (x, i) : iter.byenum([1,3,5,7,9][:]) std.assert(x == n, "invalid enum idx {}", x) std.assert(i == n*2 + 1, "invalid enum val {}", i) n++ ;; }