Where can I find the code for Arduino's "attachInterrupt"? Where can I find the code for Arduino's attachInterrupt function?

A search on the Arduino's Github repo yielded nothing.

I suspect it might be a wrapper for some avr-libc function but nothing in the avr-libc docs stands out to me...
It's in the core in WInterrupts.c

On my install it's at:

arduino-1.8.5/hardware/arduino/avr/cores/arduino/WInterrupts.c