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diff --git a/61-69/64.hs b/61-69/64.hs
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+data Tree a = Empty | Branch a (Tree a) (Tree a) deriving (Show, Eq)
+
+layout :: Tree Char -> Tree (Char, (Int, Int))
+
+layout t = fst $ draw t 1 1
+    where draw Empty x _ = (Empty, x)
+          draw (Branch v l r) x y =
+              (Branch (v, (x', y)) lt rt, x'')
+                  where (lt, x') = draw l x (y + 1)
+                        (rt, x'') = draw r (x' + 1) (y + 1)