Everything required to rebuild a level of the tree and all below it. To recreate the level we add the focus node between the lefts and the rights then add this forest to the parent value to get a tree.
lefts
rights
The underlying type of the tree.
All children of the parent that are to the left of the focus node.
Parent node value of the focus node at the level we are encoding. All nodes have a parent except the root node.
All children of the parent that are to the right of the focus node.
Everything required to rebuild a level of the tree and all below it. To recreate the level we add the focus node between the
leftsand therightsthen add this forest to the parent value to get a tree.