def METHOD_NAME(self, filename):
    ch_types = list(self.ch_types)
    ch_pos = self.ch_pos.tolist()
    ch_names = list(self.ch_names)
    if self.landmarks:
        n = len(self.landmarks)
        ch_types += ["Fiducial"] * n
        ch_pos += list(self.landmarks.values())
        ch_names += list(self.landmarks.keys())
    csv_reader.write_csv_positions(
        filename, ch_types, np.array(ch_pos), ch_names,
    )