public CompilationUnitSyntax RemoveTopLevelUsings(SrcDoc srcDoc)
        {
            var emptylist = new SyntaxList <UsingDirectiveSyntax>();
            var newsyntax = srcDoc.SyntaxTree.GetCompilationUnitRoot().WithUsings(emptylist);

            return(newsyntax);
        }
        public IEnumerable <UsingDirectiveSyntax> FindUsings(SrcDoc srcDoc)
        {
            //FindUsingsWalker w = new FindUsingsWalker();
            //w.Visit(srcdoc.SyntaxTree.GetRoot());
            //var usings = w.UsingStatements;
            //return usings;

            var compilationUnit = srcDoc.SyntaxTree.GetCompilationUnitRoot();

            return(compilationUnit.Usings);
        }