null_safety.dart

void main() {
  int? nullValue;
  int zeroValue, nonZeroValue;

  zeroValue = 0;
  nonZeroValue = 5;
  // nullValue = 6;
  print(hitung(nullValue, nonZeroValue));
}

int hitung(int? nullValue, int nonZeroValue) {
  if (nullValue == null) {
    return nonZeroValue;
  } else {
    return nonZeroValue + nullValue;
  }
}