Pingo has several groups of constants used for certain attributes such as pin mode (IN, OUT, ANALOG), pin state etc. Currently they are strings because that makes it easy to inspect their values. Ideally they should be enums, but there was a wide variety of enum implementations in Python, making it hard to choose. Since Python 3.4 has an Enum type in the standard library and it has been backported to work with Python 2 in the Enum34 project, Pingo should use it: https://pypi.python.org/pypi/enum34