# string.elems
assert_eq(list("abcd".elems()), ["a", "b", "c", "d"])

assert_eq(len("aaa".elems()), 3)

def test_iter():
  i = 0
  for c in "abcd".elems():
    assert_eq(c, "abcd"[i])
    i += 1
  assert_eq(i, 4)

test_iter()