In features.py all the methods of the Feature class have zero parameters, which makes them unusable since python requires self to be passed as first parameter.

Therefore

class Features(object):
    ...

    def num_features():
        ...

needs to be changed to

class Features(object):
    ...

    def num_features(self):
        ...

otherwise you receive an error: TypeError: get_xpos() takes 0 positional arguments but 1 was given