class_docstr: Check properties of an ongoing discourse.
class_docstr_tok: ["Check","properties","of","an","ongoing","discourse","."]
docstr: Add a list of background assumptions for reasoning about the discourse.
  
  When called,  this method also updates the discourse model's set of readings and threads.
  :param background: Formulas which contain background information
  :type background: list(Expression)
code: def add_background(self, background, verbose=False):
      """
      Add a list of background assumptions for reasoning about the discourse.
  
      When called,  this method also updates the discourse model's set of readings and threads.
      :param background: Formulas which contain background information
      :type background: list(Expression)
      """
      from nltk.sem.logic import Expression
  
      for count, e in enumerate(background):
          assert isinstance(e, Expression)
          if verbose:
              print("Adding assumption %s to background" % count)
          self._background.append(e)
  
      # update the state
      self._construct_readings()
      self._construct_threads()
  
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 15 for calling the DiscourseTester obj's underlying member method code with example usage: obj.add_background(background, verbose) without return types