code: def discourse_demo(reading_command=None):
      """
      Illustrate the various methods of ``DiscourseTester``
      """
      dt = DiscourseTester(
          ["A boxer walks", "Every boxer chases a girl"],
          reading_command,
      )
      dt.models()
      print()
      # dt.grammar()
      print()
      dt.sentences()
      print()
      dt.readings()
      print()
      dt.readings(threaded=True)
      print()
      dt.models("d1")
      dt.add_sentence("John is a boxer")
      print()
      dt.sentences()
      print()
      dt.readings(threaded=True)
      print()
      dt = DiscourseTester(
          ["A student dances", "Every student is a person"],
          reading_command,
      )
      print()
      dt.add_sentence("No person dances", consistchk=True)
      print()
      dt.readings()
      print()
      dt.retract_sentence("No person dances", verbose=True)
      print()
      dt.models()
      print()
      dt.readings("A person dances")
      print()
      dt.add_sentence("A person dances", informchk=True)
      dt = DiscourseTester(
          [
              "Vincent is a boxer",
              "Fido is a boxer",
              "Vincent is married",
              "Fido barks",
          ],
          reading_command,
      )
      dt.readings(filter=True)
      import nltk.data
  
      background_file = os.path.join(
          "grammars", "book_grammars", "background.fol"
      )
      background = nltk.data.load(background_file)
  
      print()
      dt.add_background(background, verbose=False)
      dt.background()
      print()
      dt.readings(filter=True)
      print()
      dt.models()
  
imports: import os
  from abc import ABCMeta, abstractmethod
  from functools import reduce
  from operator import add, and_
  from nltk.data import show_cfg
  from nltk.inference.mace import MaceCommand
  from nltk.inference.prover9 import Prover9Command
  from nltk.parse import load_parser
  from nltk.parse.malt import MaltParser
  from nltk.sem.drt import AnaphoraResolutionException, resolve_anaphora
  from nltk.sem.glue import DrtGlue
  from nltk.sem.logic import Expression
  from nltk.tag import RegexpTagger
label_desc: Use image node_id 2 for calling a global function with example usage: discourse_demo(reading_command) without return types