private static int GetAllDocumentTypesCount(CompilationUnitSyntax root)
        {
            var walker = new TypeWalker();

            walker.Visit(root);
            return(walker.AllTypes.Count());
        }
        private static IEnumerable <TypeDeclarationSyntax> ListDocumentClassesAndStructs(CompilationUnitSyntax root)
        {
            var walker = new TypeWalker();

            walker.Visit(root);
            return(walker.ClassesAndStructs);
        }