public static string GetPageName(this Folder folder, FileCollection files, string filename) { var index = 0; var pageName = $"{filename}{FileExtension}"; var pageUrl = $"{folder.ServerRelativeUrl}/{pageName}"; while (files.Any(file => file.ServerRelativeUrl == pageUrl)) { index++; pageName = $"{filename}{index}{FileExtension}"; pageUrl = $"{folder.ServerRelativeUrl}/{pageName}"; } return(pageName); }