Parameter Passing Issue after support class

[toaction]

After introducing Python classes, Python objects now have specific types instead of all being *py.Object. For example, we can create a Dog instance through the constructor:

type Dog struct {
    py.Object
}

dog := NewDog(py.Str("dahuang"))

However, the obtained Python object can only call struct methods and cannot be passed as a parameter to functions or methods, which is obviously inconsistent with Python syntax.
Python demo:

def say(dog):
    pass

LLGo Binding:

//go:linkname Say py.say
func Say(dog *py.Object) *py.Object

LLGo use:

Say(dog)

Fault:

cannot use dog (variable of type *Dog) as *py.Object value in argument