add method
Adds value
to the end of this list,
extending the length by one.
The list must be growable.
final numbers = [1, 2, 3].notifier;
numbers.add(4);
print(numbers); // [1, 2, 3, 4]
Implementation
@override
void add(E value) {
_updateOnAction(() => this.value.add(value));
}