isBalanced :: Tree1c -> Bool
isBalanced (Node1c _ t1 t2) = (isBalanced t1) && (isBalanced t2) && abs(depth t1 - depth t2) <= 1
isBalanced :: Tree1c -> Bool
isBalanced (Node1c _ t1 t2) = (isBalanced t1) && (isBalanced t2) && abs(depth t1 - depth t2) <= 1
isBalanced (Node1c _ t1 t2) = (isBalanced t1) && (isBalanced t2) && abs(depth t1 - depth t2) <= 1