ref: 7cd4f442cf238c5de486b54deb0bfd3a3f7a0516
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++
;;
}