How does the SeqGAN model generate variable length sequences?

[bhashithe]

I think the title explains what I need to understand.

I am trying to learn GANs so I started to build the models on my own taking the SeqGAN model as a base. So what i did was change the Discriminator to an BiLSTM model.

When I ran these models, they produced variable length sentences from the data that i gave as input. However even though I used pack->lstm->unpack inside the generator I cannot see variable length sequences when I sample the generator. How did you achieve this?