fn correct_parent_link(self) {
        // Create backpointer without invalidating other references to the node.
        let ptr = unsafe { NonNull::new_unchecked(NodeRef::as_internal_ptr(&self.node)) };
        let idx = self.idx;
        let mut child = self.descend();
        child.set_parent_link(ptr, idx);
    }
Inserts a new key-value pair between the key-value pairs to the right and left of
t
benchmarks/haystacks/code/rust-library.rs