code: public static <T, R> Callable<R> andThen(Callable<T> callable, Function<T, R> resultHandler){
          return () -> resultHandler.apply(callable.call());
      }
docs: Returns a composed function that first applies the Callable and then applies
  the resultHandler.
  
  @param <T> return type of callable
  @param <R> return type of handler
  @param resultHandler the function applied after callable
  @return a function composed of supplier and resultHandler