docs: public static final <T> Stream<T> insertStreamAt(final Stream<T> stream1, final int pos, final Stream<T> insert) {
          final Tuple2<Stream<T>, Stream<T>> Tuple2 = duplicatePos(stream1, pos);
  
          return appendStream(appendStream(Tuple2._1().limit(pos), insert), Tuple2._2().skip(pos));
      }