There is a discus project on github that already implements this feature but its unmaintained now and only had declared support for django 1.4
I am using a much simpler bitfield technique in current projects, but it had significant limitations (which are not an issue in their context)
I wanted a good exercise to understand how to use the contribute_to_class method
when implementing custom fields in Django/class attributes in Python. Specifically
I wanted to figure out how to be able to create the functionality of putting methods on
a field (e.g. mymodel.myfield.do_something(foo), where myfield still holds a value)
So rather than pick up the existing project to modernize it, which actually doesn't cover the specific goal I wanted to learn, I worked on the very simple code and implementation I already had, and significantly improved it.