public static string GetAppropriateSingularOrPluralTerm( this DateTimeInterval instance, double qty, IStringLocalizer localizer = null) { switch (qty) { case 1: return(instance.GetSingularTerm().Localize(localizer)); case 2: return(instance.GetDualTerm().Localize(localizer)); default: return(instance.GetPluralTerm().Localize(localizer)); } }