toggle method

List<E> toggle(
  1. E value, [
  2. bool? exist,
  3. int newIndex = 0
])

Implementation

List<E> toggle(E value, [bool? exist, int newIndex = 0]) {
  final a = use;
  exist ??= a.contains(value);
  if (exist) {
    a.remove(value);
  } else {
    if (newIndex > -1) {
      a.insert(newIndex, value);
    } else {
      a.add(value);
    }
  }
  return a;
}