OK, I thought so.
( OK ( , ( I ( ( thought so ) . ) ) ) )
(ROOT (S (INTJ (UH OK)) (, ,) (NP (PRP I)) (VP (VBD thought) (ADVP (RB so))) (. .)))
I was very surprised by that, I had not suspected it. 
( ( I ( was ( very ( surprised ( by that ) ) ) ) ) ( , ( I ( ( ( had not ) ( suspected it ) ) . ) ) ) )
(ROOT (S (S (NP (PRP I)) (VP (VBD was) (ADJP (RB very) (VBN surprised) (WHPP (IN by) (WHNP (WDT that)))))) (, ,) (NP (PRP I)) (VP (VBD had) (RB not) (VP (VBN suspected) (NP (PRP it)))) (. .)))