iterator property

Iterator<List<T>> iterator
override

Returns an iterator that combines values of the iterables' iterators as long as they all have values.

Implementation 

Iterator<List<T>> get iterator {
  var iterators = _iterables.map((x) => x.iterator).toList(growable: false);
  // TODO(lrn): Return an empty iterator directly if iterators is empty?
  return new _IteratorZip<T>(iterators);
}