class Proxy(object):
    def __init__(self, instance):
        self.__dict__['_instance'] = instance
    def __getattr__(self, key):
        if key == '_instance': return self.__dict__['_instance']
        else: return getattr(self._instance, key)
    def __setattr__(self, key, value):
        return setattr(self._instance, key, value)

class SomeClass(object):
    def foo(self):
        return 42

x = SomeClass()
p = Proxy(x)

print p.foo() # 42
p.bar = 1
print x.bar # 1