seen it all before in one form or another 
(ROOT (S (VP (VBN seen) (NP (NP (PRP it)) (NP (DT all))) (ADVP (RB before)) (PP (IN in) (NP (NP (CD one) (NN form)) (CC or) (NP (DT another)))))))
(ROOT (S (VP (VBN ) (NP (NP (PRP )) (NP (DT ))) (ADVP (RB )) (PP (IN ) (NP (NP (CD ) (NN )) (CC ) (NP (DT )))))))