laughinghan/mathquill — comment on commit 74bb48343ed0b72556b894a073c7ea437fc2e6d0
File:  line 0
By jayferd:

If you have those two functions, your `siblingify` looks like this:

``` js

function siblingify(self, parent, prev, next, prev_next, next_prev) {
prev.parent = next.parent = parent;
setNext(prev, prev_next);
setPrev(next, next_prev);

return self;
}
```