where is the latent vector stored?

[WinterSoilder]

Hi how do i attain the latent vector to control over my results? in generate_sample.py you have give a input param dlatent like this:

    parser.add_argument("--input", action="store", type=str,
                        default=None, help="the dlatent code (W) for a certain sample")

where do I get this from? does it get generated after training is complete? More specifically say I want control over facial expression in what ways do I train my model that i can infer facial expression.

Thanks