What can one do with an existing model?

I'm curious about how one might use this without `--is_train`. I can load a model successfully, but it's not clear if there is anything in place to use it.

For instance, I would like to explore the latent space in a given region and show its linearity. Is there any simple way to input different values and output images?

Start by tracing the existing --is_train handling and the path used to load an existing model. Determine whether the current entry points support supplying latent-space values and producing images; done means the supported inference workflow and its limits are clear, with a reproducible way to explore a chosen region.

Written by the indexing model from the issue text.