groupSetsBy<K> method
*<Null safety>*
Map<K, Set<T>> groupSetsBy <K>(K keyOf(T element))
Implementation
Map<K, Set<T>> groupSetsBy<K>(K Function(T element) keyOf) {
var result = <K, Set<T>>{};
for (var element in this) {
(result[keyOf(element)] ??= <T>{})..add(element);
}
return result;
}