to keep upping the ante on each other , just as their characters do in the film 
(ROOT (S (VP (TO to) (VP (VB keep) (S (VP (VBG upping) (NP (DT the) (NN ante)) (PP (IN on) (NP (DT each) (JJ other))))) (, ,) (SBAR (ADVP (RB just)) (IN as) (S (NP (PRP$ their) (NNS characters)) (VP (VBP do) (PP (IN in) (NP (DT the) (NN film))))))))))
(ROOT (S (VP (TO ) (VP (VB ) (S (VP (VBG ) (NP (DT ) (NN )) (PP (IN ) (NP (DT ) (JJ ))))) (, ) (SBAR (ADVP (RB )) (IN ) (S (NP (PRP$ ) (NNS )) (VP (VBP ) (PP (IN ) (NP (DT ) (NN ))))))))))