Demonstrates that data descriptors have precedence over the instance dict.

magic_precedence.py

class NonDataDescriptor(object):
    def __get__(self, *args, **kwargs):
        return 'magic'

class DataDescriptor(object):
    def __get__(self, *args, **kwargs):
        return 'magic'

    def __set__(self, *args, **kwargs):
        pass


class MyObject(object):
    ndd = NonDataDescriptor()
    dd = DataDescriptor()

    def __init__(self):
        self.ndd = "non-data"
        self.dd = "data"


ob = MyObject()
print(ob.ndd)
print(ob.dd)

Output:

$ python2 magic.py
non-data
magic