Confuse about invoking-descriptors

Direct Call

The simplest and least common call is when user code directly invokes a descriptor method: x.__get__(a).

what is x and how to run this demo code?

x is a descriptor, for instance a property or a method:

class A:
    def __init__(self, x):
        self._x = x
    @property
    def x(self):
        return self._x
    def func(self):
        return self._x

Now

>>> a = A(42) 
>>> a.x
42
>>> A.x.__get__(a)
42
>>> A.func.__get__(a)()
42

Thanks a lot, I miss the ‘A’ before ‘x’