code: def entity_categories(self, candidates):
      candidate_features = {}
      for candidate in candidates:
          f = self._features.category(candidate)
          f = [
              "http://dbpedia.org/resource/Category:%s" % c
              for c in f.split()
          ]
          if f:
              candidate_features[candidate] = f
      return candidate_features
  
imports: from sematch.utility import FileIO
  from nltk.stem import WordNetLemmatizer
  from nltk.corpus import wordnet
  import nltk
  from collections import Counter
  import itertools
  import string
  import re
label_desc: Use image node_id 7 for calling the FeatureExtractor obj's underlying member method code with example usage: obj.entity_categories(candidates) and returns: candidate_features