forEachAsync<V>  function 
 
Iterable elements of source with support async function and runs it's in parallels
Implementation
Future<void> forEachAsync<V>(
    Iterable<V> source, Future<void> Function(V elemente) forEach,
    [int parallels = 1]) async {
  for (final Iterable<V> group in groupBySize<V>(source, parallels)) {
    await Future.wait(group.map(forEach));
  }
}