I've gotta create a bidirectional communication protocol to link 2-3 RPis over GPIO. I have between 4-5 pins for TX and 45 for RX, so each directional bus is that wide.
Even better, I have to assume 4 bit bus length unless told otherwise, since 4 to 6 pins on the GPIO are usually used for serial/UART, COM and/or 1-pin communications (for use to get a console, not to throw data down.)

The best part?

Needs to be a Python library.

i wanna die