\begin{center}\begin{minipage}{15cm}\begin{Verbatim}[frame=single]
> a = 3;
> b = 4;
> if (a == b) then print("Hello world");
> b = 3;
> if (a == b) then print("Hello world");
Hello world
> if (a == b) then print("You are telling the truth") else print("Liar!");
You are telling the truth
\end{Verbatim}
\end{minipage}\end{center}
