Map model name to model network configuration.

def get_model_config(model_name, dataset):
    """Map model name to model network configuration."""
    model_map = _get_model_map(dataset.name)
    if model_name not in model_map:
        raise ValueError("Invalid model name \"%s\" for dataset \"%s\"" %
                         (model_name, dataset.name))
    else:
        return model_map[model_name]()