Oh I've done that a number of times.
( Oh ( I ( ( 've ( done ( that ( ( a number ) ( of times ) ) ) ) ) . ) ) )
(ROOT (S (ADVP (RB Oh)) (NP (PRP I)) (VP (VBP 've) (VP (VBN done) (PP (IN that) (NP (NP (DT a) (NN number)) (PP (IN of) (NP (NNS times))))))) (. .)))
I haven't done that.
( I ( ( ( have n't ) ( done that ) ) . ) )
(ROOT (S (NP (PRP I)) (VP (VBP have) (RB n't) (VP (VBN done) (NP (DT that)))) (. .)))