def format_timespan_digits(ts):
    """Format a timespan namedtuple as a string resembling a digital display."""
    if ts.days:
        day_or_days = "days" if ts.days > 1 else "day"
        return (
            f"{ts.days} {day_or_days}, "
            f"{ts.hours:02d}:{ts.minutes:02d}:{ts.seconds:02d}"
        )
    if ts.seconds:
        return f"{ts.hours:02d}:{ts.minutes:02d}:{ts.seconds:02d}"
    return f"00:00:00.{ts.total_microseconds}"