class A(object):
    def __init__(self):
        self.x = 5
    def __getattr__(self, name):
        print('A.__getattr__(', self, ',', name, ')')
        setattr(self, name, 10)
        return 10
    def __setattr__(self, name, value):
        print('A.__setattr__(', self, ',', name, ',', value, ')')
        self.__dict__[name] = value

a = A()
print('P1:', a.x)
print('P2:', a.x)
a.x = 15
print('P3:', a.x)

print('P4:', a.y)
print('P5:', a.y)
a.y = 20
print('P6:', a.y)