, it throws you for a loop . 
(ROOT (S (, ,) (NP (PRP it)) (VP (VBZ throws) (NP (PRP you)) (PP (IN for) (NP (DT a) (NN loop)))) (. .)))
(ROOT (S (, ) (NP (PRP )) (VP (VBZ ) (NP (PRP )) (PP (IN ) (NP (DT ) (NN )))) (. )))