Overriding inherited properties’ getters and setters in Python

To override a setter in python 2 I did this:

class A(object):
    def __init__(self):
        self._attr = None

    @property
    def attr(self):
        return self._attr

    @attr.setter
    def attr(self, value):
        self._attr = value


class B(A):
    @A.attr.setter
    def attr(self, value):
        # Do some crazy stuff with `value`
        value = value[0:3]
        A.attr.fset(self, value)

To understand where A.attr.fset came from see the documentation on the property class:
https://docs.python.org/2/library/functions.html#property