\begin{saveblock}{demo}
	\begin{highlightblock}[gobble=8,linewidth=0.6\textwidth,
		framexleftmargin=0.25em,xleftmargin=0.25em]
        \renewcommand\thesubsection
        {(\thesection)\alph{subsection}}

        \section{AA}
        \subsection{BB}
        \subsection{CC}
        \subsection{DD}
        \section{EE}
        \subsection{FF}
    \end{highlightblock}
\end{saveblock}

\begin{frame}{\lang,Counter formatting,Counter-formattering,}
	% \useblock{setcounter}

    % \medskip

	% \centering
    % \includegraphics[width=\linewidth,height=0.4\textheight,keepaspectratio]{
	% 	assets/internals-setcounter-output.pdf}

    \begin{columns}
        \begin{column}{0.4\textwidth}
            \adjustbox{fbox=1pt 5pt}{\includegraphics[width=\linewidth,height=0.6\textheight,keepaspectratio]{
	        assets/internals-counter_formatting-with-output.pdf}}
        \end{column}
        \begin{column}{0.6\textwidth}
            \only<1>{\useblock{demo}}
            \unless\ifishandout
                \only<2->{\adjustbox{fbox=1pt 5pt}{\includegraphics[width=0.6667\textwidth,height=0.6\textheight,keepaspectratio]{
                assets/internals-counter_formatting-without-output.pdf}}}
            \fi
        \end{column}
    \end{columns}
\end{frame}