public static boolean isBinaryTreeABinarySearchTree(bNode root){
        if(root == null) return true;
        if(root.left != null){
            if(root.left.data > root.data) return false;
        }
        if(root.right != null){
            if(root.right.data <= root.data) return false;
        }

        return isBinaryTreeABinarySearchTree(root.left) && isBinaryTreeABinarySearchTree(root.right);
    }