Espruino - Where to find default implementations?

Hi.

I have some questions about the included implementations of different firmwares.

1. I'm looking for the implementations like "Graphics.createArrayBuffer". Where i can find them?
   
2. I also recognize, that the firmwares (for pico and esp8266) aren't the same. Where i can find the differents? For example the esp8266 firmware dont know the "Graphics" module. I would like to add this so esp8266.
   
   

Can someone send me the right place to look for?