func get_time_start() -> String {
    let dateFormatter = DateFormatter()
    dateFormatter.locale = Locale(identifier: "fr_FR")
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
    let timeStart = dateFormatter.date(from: time_start)
    dateFormatter.dateFormat = "hh:mm"
    return dateFormatter.string(from: timeStart!);
}