static noeq record IntPair(int a, int b) {
  public boolean equals(Object o) {
    if (!o instanceof IntPair) false;
    IntPair x = cast o;
    return a == x.a && b == x.b;
  }

  public int hashCode() {
    int h = -672893111;
    h = boostHashCombine(h, _hashCode(a));
    h = boostHashCombine(h, _hashCode(b));
    return h;
  }
}