Usage of this library...

Forgive me if this a stupid question but... What is the need/use for this libary? I ask because I see in the [GD32V examples repo](https://github.com/sipeed/platform-gd32v/blob/master/examples/arduino-blink/src/Blink.cpp) you see this with the Arduino Blink example:

`#include <Arduino.h>`

I'm wondering what is the difference in including Arduino.h vs Longduino? 
