foo(int a, int b){
  if (a == null or b == null){
    return null;
  }
}

foo2(int a, int b, int c){
  if (a == null or b == null or c == null){
    return null;
  }
}

bar(int a, int b){
  if (a == null and b == null){
    return null;
  }
}

bar2(int a, int b, int c){
  if (a == null and b == null and c == null){
    return null;
  }
}