# File lib/maruku/ext/math/to_html.rb, line 66
      def render_png(kind, tex)
        engine = get_setting(:html_png_engine)
        method = "convert_to_png_#{engine}".to_sym
        return self.send(method, kind, tex) if self.respond_to? method

        raise "A method called #{method} should be defined."
        nil
      end