function insert_nonoverlapping($shift)
{
    $other_shifts = get_master_shifts($shift->get_schedule_type(), $shift->get_day());
    foreach ($other_shifts as $other_shift) {
        if (masterslots_overlap($shift->get_start_time(), $shift->get_end_time(), $other_shift->get_start_time(), $other_shift->get_end_time())) {
            return false;
        }
    }
    insert_dbMasterSchedule($shift);
    return true;
}
function insert_nonoverlapping($shift)
{
    $other_shifts = get_master_shifts($shift->get_group(), $shift->get_day(), $shift->get_week_no());
    foreach ($other_shifts as $other_shift) {
        if (masterslots_overlap($shift, $oher_shift)) {
            return false;
        }
    }
    insert_dbMasterSchedule($shift);
    return true;
}