by things best cluster , <apostrophe><apostrophe>
(ROOT_0 (S_0 (ATS_2 (PP_2 (IN_0 by) (NP_3 (ATNP_1 (NP_4 (NNS_1 things)) (JJS_0 best)) (NN_1 cluster))) (COMMA_0 ,)) (APOSTROPHE_0 <apostrophe><apostrophe>)))