def to_osm_format(data):
    """ OSM "opening_hours" tag field format

    SEE: https://wiki.openstreetmap.org/wiki/Key:opening_hours
    """
    txt = ''
    for dow in 'Su Mo Tu We Th Fr Sa'.split():
        day_hours = data.get(dow, None)
        if day_hours is not None:
            txt += (
                f'{dow} {day_hours[0].hour}:{day_hours[0].minute}-{day_hours[2].hour}:{day_hours[1].minute}; '
                )
    return txt.rstrip().rstrip(';')
