Make.XFTransformation/Traversal over nodes
Recursively traverse node, applying pre to each element, then apply post to the result
Bounded fix point combinator, applies f to v until v' = v or bound reaches 0
Bounded fix point combinator, applies f to v until f v = v or bound reaches 0
Recursively traverse node applying f to each element until node reaches a fix point or bound reaches 0
Iterate over all elements of node applying a (side-effectful) f. Short-circuits when f invokes iterated