\begin{center}\begin{minipage}{15cm}\begin{Verbatim}[frame=single]
> add = proc(m,n) { var res; res := m + n; return res; };
> add(5,6);
11
> hey = proc() { print("Hello world."); };
> hey();
Hello world.
> print(hey());
Hello world.
void
> hey;
proc()
{
print("Hello world.");
return void;
}
\end{Verbatim}
\end{minipage}\end{center}
