mapToggleValue<K, V> static method
Toggles a value in a map of lists.
If add is null, toggles based on current presence.
If add is true, adds the value. If false, removes it.
Implementation
static void mapToggleValue<K, V>(Map<K, List<V>> map, K key, V value, {bool? add}) {
if (value == null) return;
add ??= !mapContainsValue(map, key, value);
if (add) {
mapAddValue(map, key, value);
} else {
mapRemoveValue(map, key, value);
}
}