assignAll method
Replaces all existing items of this list with items
Implementation
void assignAll(Iterable<E> items) {
  // if (this is RxSet) {
  //   (this as RxSet)._value;
  // }
  clear();
  addAll(items);
}Replaces all existing items of this list with items
void assignAll(Iterable<E> items) {
  // if (this is RxSet) {
  //   (this as RxSet)._value;
  // }
  clear();
  addAll(items);
}