Initialize a Face object from a json dictionary.

def _from_dict(cls, _dict):
        """Initialize a Face object from a json dictionary."""
        args = {}
        if 'age' in _dict:
            args['age'] = FaceAge._from_dict(_dict.get('age'))
        if 'gender' in _dict:
            args['gender'] = FaceGender._from_dict(_dict.get('gender'))
        if 'face_location' in _dict:
            args['face_location'] = FaceLocation._from_dict(
                _dict.get('face_location'))
        return cls(**args)