@propety. When is fget not None?

Question

Python

property(fget=None, fset=None, fdel=None, doc=None)

If I see this:

class C(object):
    def getx(self): return self.__x
    def setx(self, value): self.__x = value
    def delx(self): del self.__x
    x = property(getx, setx, delx, "I'm the 'x' property.")

then everything is clear. But then, for me, everything is not clear:

class C:
    def __init__(self):
        self._x = None

    @property
    def x(self):
        """I'm the 'x' property."""
        return self._x

    @x.setter
    def x(self, value):
        self._x = value

    @x.deleter
    def x(self):
        del self._x

Python that, immediately runs through the entire class object in search of methods, which he then spreads on fget, fset, so that they are not None?