How to convert my custom dataset to rec file with rec_builder.py?

Hi, since there is no guide here so I think at first I must have a training dataset just like faces_emore but when I use common/rec_builder.py, I got this:
Is there any tutorial on how to train a new recognition model? :(

The issue names common/rec_builder.py and the faces_emore dataset; start by reading that script and the attached error output. Document the required custom-dataset layout, the steps to produce a rec file, and how to train a recognition model, with a successful conversion and training run as the completion criteria.

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