\ifger{Wir bauen unseren Tree:}{Let's build our tree:}
\begin{haskellcode}
tree :: Tree
tree = Node
       (Leaf 'x')
       1
       (Node
            (Leaf 'y')
            2
            (Leaf 'z')
       )
\end{haskellcode}
\ifger{Siehe Tafel...}{See board...}