for! "aaa", a =>
    print! a + 1 # ERR

for! zip([1+1], ["a"+"b"]), ((i, s),) => # i: Nat, s: Str
    print! i + 1
    print! s + "b"
    print! i + "a" # ERR

for! {"a": 1}, s =>
    print! s + 1 # ERR
