code: public static Function<? super ReactiveSeq<Long>, ? extends ReactiveSeq<Long>> concatLongs( ReactiveSeq<Long> b){
          return a->ReactiveSeq.fromSpliterator(LongStream.concat(a.mapToLong(i->i),b.mapToLong(i->i)).spliterator());
      }
docs: /*
  Fluent integer concat operation using primitive types
  e.g.
  <pre>
  {@code
  import static cyclops.ReactiveSeq.concatLongs;
  
  ReactiveSeq.ofLongs(1l,2l,3l)
  .to(concatLongs(ReactiveSeq.ofLongs(5,10)));
  
  //[1l,2l,3l,5l,6l,7l,8l,9l]
  }
  </pre>