\newcommand{\alg}[1]{\text{\bf #1}}
\newcommand{\setmerge}{\alg{merge}}
\newcommand{\setmergeof}[3]{\setmerge\mergeof{#1}{#2}{#3}}
+\newcommand{\stmtmergeof}[3]{\setmerge\mergeof{#1}{#2}{#3}}
%\newcommand{\setmergeof}[3]{\setmerge\left\lgroup #1 \;\middle\lmoustache\; #2 \;\middle\rmoustache\; #3 \right\rgroup}
%\newcommand{\setmergeof}[3]{\setmerge\left\rmoustache #1 \middle\rmoustache #2 \middle\lmoustache #3 \right\lmoustache}