/// <summary>
/// Returns the date of the first day of the week starting on <paramref name="startOfWeek" />, which contains <paramref name="date"/>.
/// </summary>
/// <param name="date"></param>
/// <param name="startOfWeek"></param>
/// <returns></returns>
public static DateTimeOffset StartOfWeek(this DateTimeOffset date, DayOfWeek startOfWeek = DayOfWeek.Sunday)
{
return(DDRIT.StartOfWeek(date, startOfWeek));
}