\begin{flushleft}
\hrulefill

\vspace*{-4mm}

\begin{alltt}
STk> (define g (graph '(1 2 3) '((1 2) (1 3) (3 1)))){\em{
\#[undefined]} }
\end{alltt}
\begin{alltt}
STk> (set-string-attribute! 'vcolor "red" (vertex-ref g 1)){\em{
\#[undefined]} }
\end{alltt}
\begin{alltt}
STk> (map (lambda (x) (find-string-attribute 'vcolor x)) 
		(set-vertex->list (vertices g))){\em{
("blue" "red" "blue")} }
\end{alltt}

\vspace*{-5mm}

\hrulefill
\end{flushleft}