public static string ToLaTeX(this DocumentPart part)
        {
            var visitor = new ToLaTeXVisitor();

            part.Accept(visitor);
            return(visitor.LaTeX);
        }
        public static string ToHtml(this DocumentPart part)
        {
            var visitor = new ToHtmlVisitor();

            part.Accept(visitor);
            return(visitor.HtmlText);
        }
        public static string ToPlainText(this DocumentPart part)
        {
            var visitor = new ToPlainTextVisitor();

            part.Accept(visitor);
            return(visitor.PlainTextString);
        }