if i want music , i 'll buy the soundtrack . 
(ROOT (S (SBAR (IN if) (S (NP (PRP i)) (VP (VBP want) (NP (NN music))))) (, ,) (NP (PRP i)) (VP (MD 'll) (VP (VB buy) (NP (DT the) (NN soundtrack)))) (. .)))
(ROOT (S (SBAR (IN ) (S (NP (PRP )) (VP (VBP ) (NP (NN ))))) (, ) (NP (PRP )) (VP (MD ) (VP (VB ) (NP (DT ) (NN )))) (. )))