class_docstr: An index that can be used to look up the offset locations at which
  a given word occurs in a document.
code: def __repr__(self):
      return "<ConcordanceIndex for %d tokens (%d types)>" % (
          len(self._tokens),
          len(self._offsets),
      )
  
imports: import re
  import sys
  import unicodedata
  from collections import Counter, defaultdict, namedtuple
  from functools import reduce
  from math import log
  from nltk.collocations import BigramCollocationFinder
  from nltk.lm import MLE
  from nltk.lm.preprocessing import padded_everygram_pipeline
  from nltk.metrics import BigramAssocMeasures, f_measure
  from nltk.probability import ConditionalFreqDist
  from nltk.probability import FreqDist
  from nltk.tokenize import sent_tokenize
  from nltk.util import LazyConcatenation, cut_string, tokenwrap
label_desc: Use image node_id 4 for calling the ConcordanceIndex obj's underlying member method code with example usage: obj.__repr__() and returns: unknown