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.