code: public static <T, R> FluentFunctions.FluentFunction<T, R> of(final Function<T, R> fn) {
          return new FluentFunction<>(
                                      fn);
      }
docs: Construct a FluentFunction from a Function
  
  <pre>
  {@code
  FluentFunctions.of(this::addOne)
  .around(advice->advice.proceed(advice.param+1))
  .println()
  .applyHKT(10)
  }
  </pre>
  @param fn Function
  @return FluentFunction