public static string ToStr(this Severity severity, string format = null) { if (format == null) { return(severity.ToStrN()); } switch (format) { case "u": case "U": return(severity.ToStrU()); case "l": case "L": return(severity.ToStrL()); case "G": case "g": case "": case "F": case "f": return(severity.ToStrN()); default: return(severity.ToString(format)); } }