union method

MultiSet<T> union(MultiSet<T> other)

Implementation

MultiSet<T> union(MultiSet<T> other) {
  final result = MultiSet<T>();
  for (final key in _elements.keys) {
    result._elements[key] = _elements[key]!;
  }
  for (final key in other._elements.keys) {
    result._elements[key] =
        (result._elements[key] ?? 0) + other._elements[key]!;
  }
  return result;
}