static public string ToHoursMinutesSecondsMillisecondsString(this Duration item)
{
int hours;
int minutes;
int seconds;
int milliseconds;
item.GetHoursMinutesSecondsMilliseconds(out hours, out minutes, out seconds, out milliseconds);
return(hours + ":" +
minutes.ToString("D2") + ":" +
seconds.ToString("D2") + "." +
milliseconds.ToString("D3"));
}