contains method Null safety

  1. @override
bool contains(
  1. Object? element
)

Checks if item is any of the ZipItem entries, if the item is a ZipItem checks if it is in the base list itself.

Implementation

@override
bool contains(Object? element) {
  if (element is ZipItem){
    return _base.contains(element);
  }
  for (ZipItem<I1, I2> item in _base) {
    if (item.item1 == element) {
      return true;
    }
    if (item.item2 == element) {
      return true;
    }
  }
  return false;
}