concatWithMultipleList method
Return a list concatenates the output of the current list and multiple iterables
Implementation
List<T> concatWithMultipleList(List<Iterable<T>> iterables) {
if (isEmptyOrNull || iterables.isEmptyOrNull) return [];
final list = iterables.toList(growable: false).expand((i) => i);
return <T>[...this.orEmpty(), ...list];
}