update method

V update(
  1. K key,
  2. V update(
    1. V value
    ), {
  3. V ifAbsent()?,
})

Implementation

V update(K key, V Function(V value) update, {V Function()? ifAbsent}) {
  final result = value.update(key, update, ifAbsent: ifAbsent);
  set(value, force: true);
  return result;
}