Since Python 3 removed unbound methods, I found some references using the old terminology in this HowTo about descriptors (https://docs.python.org/3/howto/descriptor.html). Also, since unbound methods have been removed, the function call types.MethodType now only takes two arguments, namely the function to bind and the object to bind to. In the current documentation, however, the old function call with three arguments is still being used.

I made a pull request on github, then I realized that it is just a mirror repo. Attached you will see a patch file with some of the obvious changes that could me made to the document