internal static string PathForSettingsFile(string workbookPath)
{
//Sanity test
if(string.IsNullOrWhiteSpace(workbookPath))
{
AppDiagnostics.Assert(false, "missing path");
throw new ArgumentNullException("missing path");
}
//Tag an extra extension to the file
return workbookPath + WorkbookSettingsSuffix;
}