Thank you so much.
I also happen to find that
z = self.encoder(img) works as well, after I posted this inquiry.
However, I still don’t understand what * means here.
Typically *  means pointer in c, c++
multiple arguments (*args) in python,
But, here in pytorch, I wonder whether there is a reserved function/role for * ?
It appears that * is related with generator, but I’m not sure how it works,