\begin{flushleft}
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\vspace*{-4mm}

\begin{alltt}
STk> (define v (vertex-ref g 1)){\em{
\#[undefined]} }
\end{alltt}
\begin{alltt}
STk> (define w (vertex-ref dg 1)){\em{
\#[undefined]} }
\end{alltt}
\begin{alltt}
STk> (describe (out-neighbors v)){\em{
\#[\(<\)set\(<\)vertex*\(>\)\(>\) \#p4f9950] is an instance of class \(<\)set\(<\)vertex*\(>\)\(>\)
Slots are: 
     val = \{1 3\}
\#f} }
\end{alltt}
\begin{alltt}
STk> (describe (out-neighbors w)){\em{
\#[\(<\)set\(<\)vertex*\(>\)\(>\) \#p4f9260] is an instance of class \(<\)set\(<\)vertex*\(>\)\(>\)
Slots are: 
     val = \{1\}
\#f} }
\end{alltt}

\vspace*{-5mm}

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\end{flushleft}