fn add(u8 x, u8 y) -> u8 { ret x + y; }
fn sub(u8 x, u8 y) -> u8 { ret x - y; }
fn mul(u8 x, u8 y) -> u8 { ret x * y; }
fn div(u8 x, u8 y) -> u8 { ret x / y; }
fn rem(u8 x, u8 y) -> u8 { ret x % y; }

fn lt(u8 x, u8 y) -> bool { ret x < y; }
fn le(u8 x, u8 y) -> bool { ret x <= y; }
fn eq(u8 x, u8 y) -> bool { ret x == y; }
fn ne(u8 x, u8 y) -> bool { ret x != y; }
fn ge(u8 x, u8 y) -> bool { ret x >= y; }
fn gt(u8 x, u8 y) -> bool { ret x > y; }

iter range(mutable u8 lo, u8 hi) -> u8 {
  while (lo < hi) {
    put lo;
    lo += 1u8;
  }
}