pandoc/test/command/5740.md

% pandoc -t latex
\newcommand\parenthesize[1][x]{(#1)}
$\parenthesize$, $\parenthesize[y]$, $\parenthesize[\textsc{head}]$
^D
\newcommand\parenthesize[1][x]{(#1)}

\((x)\), \((y)\), \((\textsc{head})\)