What is an anti_profile model?

[Podidiving]

Hello!
In source code there is mentioned anti profile model to determine, whether a face is frontal or not

yoloface/face_detector.py

Line 37 in 4c92a01

self.anti_profile = joblib.load(os.path.join(self._class_path, 'models/anti_profile/anti_profile_xgb_new.pkl'))

But there is no such file in models folder, nor the mentioning about that in readme

Can you please tell me, what is it and where could it be found?