def kb(self):
    return self.b / 1024

@property
def mb(self):
    return self.kb / 1024

def __add__(self, *args, **kwds):
    return BufferSize(super(BufferSize, self).__add__(*args, **kwds))
v = BufferSize(1) + BufferSize(2)
print(v, type(v))
Adding a property to an int value in python