update method

*<Null safety>*

• @override

V update (K key, V update(V), {V ifAbsent()}) override

Implementation

@override
V update(K key, V Function(V) update, {V Function()? ifAbsent}) =>
    _base.update(_canonicalize(key), (pair) {
      var value = pair.value;
      var newValue = update(value);
      if (identical(newValue, value)) return pair;
      return MapEntry(key, newValue);
    },
        ifAbsent:
            ifAbsent == null ? null : () => MapEntry(key, ifAbsent())).value;