def get_existing_model(model_name):
    try:
        model_cls = engine.get_document_cls(model_name)
        log.debug('Model `{}` already exists. Using existing one'.format(
            model_name))
        return model_cls
    except ValueError:
        log.debug('Model `{}` does not exist'.format(model_name))
Try to find existing model class named `model_name`.
dataset/ETHPy150Open ramses-tech/ramses/ramses/models.py/get_existing_model