Future lastWhere(bool test(T element), {Object defaultValue()})

Finds the last element in this stream matching test.

As firstWhere, except that the last matching element is found. That means that the result cannot be provided before this stream is done.

Source 

Future<dynamic> lastWhere(bool test(T element), {Object defaultValue()}) {
  _Future<dynamic> future = new _Future();
  T result = null;
  bool foundResult = false;
  StreamSubscription subscription;
  subscription = this.listen(
    (T value) {
      _runUserCode(
        () => true == test(value),
        (bool isMatch) {
          if (isMatch) {
            foundResult = true;
            result = value;
          }
        },
        _cancelAndErrorClosure(subscription, future)
      );
    },
    onError: future._completeError,
    onDone: () {
      if (foundResult) {
        future._complete(result);
        return;
      }
      if (defaultValue != null) {
        _runUserCode(defaultValue, future._complete, future._completeError);
        return;
      }
      try {
        throw IterableElementError.noElement();
      } catch (e, s) {
        _completeWithErrorCallback(future, e, s);
      }
    },
    cancelOnError: true);
  return future;
}