showTree :: Show a => AVLTree a -> String -> String
showTree Leaf h = "-Leaf"
showTree (Node val h Leaf Leaf) intro = "-" ++ show val
showTree (Node val h l Leaf) intro =
	"-" ++ show val ++ "\n" ++
	intro ++ " |\n" ++
	intro ++ " `" ++ showTree l (intro ++ "  ")
showTree (Node val h Leaf r) intro =
	"-" ++ show val ++ "\n" ++
	intro ++ " |\n" ++
	intro ++ " `" ++ showTree r (intro ++ "  ")
showTree (Node val h l r) intro =
	"-" ++ show val ++ "\n" ++
	intro ++ " |\n" ++
	intro ++ " +" ++ showTree l (intro ++ " |") ++ "\n" ++
	intro ++ " |\n" ++
	intro ++ " `" ++ showTree r (intro ++ "  ")


instance Show a => Show (AVLTree a) where
	show tree = showTree tree ""