def _read_dig_fif(fid, meas_info):
    """Helper to read digitizer data from a FIFF file"""
    isotrak = dir_tree_find(meas_info, FIFF.FIFFB_ISOTRAK)
    dig = None
    if len(isotrak) == 0:
        logger.info('Isotrak not found')
    elif len(isotrak) > 1:
        warn('Multiple Isotrak found')
    else:
        isotrak = isotrak[0]
        dig = []
        for k in range(isotrak['nent']):
            kind = isotrak['directory'][k].kind
            pos = isotrak['directory'][k].pos
            if kind == FIFF.FIFF_DIG_POINT:
                tag = read_tag(fid, pos)
                dig.append(tag.data)
                dig[-1]['coord_frame'] = FIFF.FIFFV_COORD_HEAD
    return dig
dataset/ETHPy150Open mne-tools/mne-python/mne/io/meas_info.py/_read_dig_fif/original