select method

@override void select(T val, { bool selected = true, })

Function to select a value

Implementation

@override
void select(T val, {bool selected = true}) {
  final List<T> values = List.from(value);
  if (selected) {
    values.add(val);
  } else {
    values.remove(val);
  }
  onChanged?.call(values);
}