filterWithKey method
Implementation
Map<K, V> filterWithKey(bool Function(K key, V value) test) => {
for (var (MapEntry(:key, :value)) in entries)
if (test(key, value)) key: value
};
Map<K, V> filterWithKey(bool Function(K key, V value) test) => {
for (var (MapEntry(:key, :value)) in entries)
if (test(key, value)) key: value
};