This "library" has been implemented according to the official SMBus v3.1 specification.
It provides functions to interface, setup and manage an SMBus network on an Arduino by mimic-ing the official Wire library (which is used in the backend after some transformation etc.).
I do not suggest you just try to use this as it is unfinished and yet to be confirmed to actually work, however feel free to share your own development by opening a pull request. The project I wanted to use this for ultimately got scrapped before I could test it. I was planning on using this to interface with a smart-battery and do some system management+monitoring on an Arduino.