Gravity: Lightning Sensor Library

I am following the tutorial on this website for the gravity lightning sensor

https://wiki.dfrobot.com/Gravity:%20Lightning%20Sensor%20SKU:%20SEN0290?gclid=CjwKCAjwrZOXBhACEiwA0EoRD2zHZowPKyxnvdmNr9kzy9XoNV6BUL1D28xa2hupRGdXim8QxWR2LRoCsWUQAvD_BwE

I have basically copied and pasted this code into the arduino IDE and installed the DFRobot_AS3935_I2C library as stated in the instructions.

However when I go to compile onto the Arduino the following line causes an error

#include "Lib_I2C.h"

I can't find this library anywhere nor is it stated in the instructions how to get the library..

Is anyone able to help me locate this?

Thanks