Method inorder

publication/code/chapter08/rbtree.rs:170–174

(&self)

    }

    unsafe fn inorder(&self) {
        if !self.left.is_null() { (*self.left).inorder(); }
        println!("key: {:?}", &self.key);
        if !self.right.is_null() { (*self.right).inorder(); }
    }

    unsafe fn postorder(&self) {
        if !self.left.is_null() { (*self.left).postorder(); }