Edge labels

You can write edge labels. They should be specified as the optional argument of \chunk. Note that the width of an edge label is neglected.

\begin{bundle}{xxx}
\chunk[left]{aaa}
\chunk{
        \begin{bundle}{yyy}
        \chunk{bbb}
        \chunk{ddd}
        \end{bundle}}
\chunk[right]{ccc}
\end{bundle}

\begin{bundle}{xxx}
\chunk[left]{aaa}
\chunk{
\begin{bundle}{yyy}
\chunk{bbb}
\chunk{ddd}
\end{bundle}}
\chunk[right]{ccc}
\end{bundle}