happens to be that rarity among sequels 
(ROOT (VP (VBZ happens) (S (VP (TO to) (VP (VB be) (NP (DT that) (NN rarity)) (PP (IN among) (NP (NNS sequels))))))))
(ROOT (VP (VBZ ) (S (VP (TO ) (VP (VB ) (NP (DT ) (NN )) (PP (IN ) (NP (NNS ))))))))