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