@Override public <R>CompletableFuture<R> collect(final Supplier<R> supplier,final BiConsumer<R,? super T> accumulator,final BiConsumer<R,R> combiner){
  return CompletableFuture.supplyAsync(null,exec);
}

@ Override public < R > CompletableFuture < R > collect ( final Supplier < R > supplier , final BiConsumer < R , ? super T > accumulator , final BiConsumer < R , R > combiner ) { return CompletableFuture . supplyAsync ( null , exec ) ; }
asynchronously perform a stream collection
