code: public static LazyReact parallelBuilder(final int parallelism) {
          return LazyReact.builder()
                          .executor(Executors.newFixedThreadPool(parallelism))
                          .build();
      }
docs: Construct a new LazyReact builder, with a new task executor and retry
  executor with configured number of threads
  
  @param parallelism
  Number of threads task executor should have
  @return LazyReact instance