Common functions for interacting with PiFace products. Also available from PyPI

http://piface.github.io/pifacecommon/

You can also find the documentation installed at:

/usr/share/doc/python3-pifacecommon/

Download the latest release from here. Then install with:

$ dpkg -i python3-pifacecommon_2.0.2-1_all.deb

You may need to reboot.