bool and (bool b1 bool b2){
  if b1 {
    if b2 { return true; }
    else { return false; }
  } else {
    return false;
  }
}

bool or (bool b1 bool b2){
  if b1 {
    return true;
  } else {
    if b2 { return true; }
    else { return false; }
  }
}

bool not (bool b) {
  if b { return false; } else { return true; }
}

bool implies (bool p bool q) {
  return (call or((call not (p)) q));
}

bool veriftranspose(bool a bool b){
  return ((call implies(a b)) = (call implies((call not(b)) (call not(a)))));
}

test{
  bool a = true;
  bool b = true;
  print (call veriftranspose(a b));
  a = true;
  b = false;
  print (call veriftranspose(a b));
}