old_contents: # Natural Language Toolkit: Chatbots
  #
  # Copyright (C) 2001-2022 NLTK Project
  # Authors: Steven Bird <stevenbird1@gmail.com>
  # URL: <https://www.nltk.org/>
  # For license information, see LICENSE.TXT
  
  # Based on an Eliza implementation by Joe Strout <joe@strout.net>,
  # Jeff Epler <jepler@inetnebr.com> and Jez Higgins <jez@jezuk.co.uk>.
  
  """
  A class for simple chatbots.  These perform simple pattern matching on sentences
  typed by users, and respond with automatically generated sentences.
  
  These chatbots may not work using the windows command line or the
  windows IDLE GUI.
  """
  
  from nltk.chat.eliza import eliza_chat
  from nltk.chat.iesha import iesha_chat
  from nltk.chat.rude import rude_chat
  from nltk.chat.suntsu import suntsu_chat
  from nltk.chat.util import Chat
  from nltk.chat.zen import zen_chat
  
  bots = [
      (eliza_chat, "Eliza (psycho-babble)"),
      (iesha_chat, "Iesha (teen anime junky)"),
      (rude_chat, "Rude (abusive bot)"),
      (suntsu_chat, "Suntsu (Chinese sayings)"),
      (zen_chat, "Zen (gems of wisdom)"),
  ]
  
  
  def chatbots():
      import sys
  
      print("Which chatbot would you like to talk to?")
      botcount = len(bots)
      for i in range(botcount):
          print("  %d: %s" % (i + 1, bots[i][1]))
      while True:
          print("\nEnter a number in the range 1-%d: " % botcount, end=" ")
          choice = sys.stdin.readline().strip()
          if choice.isdigit() and (int(choice) - 1) in range(botcount):
              break
          else:
              print("   Error: bad chatbot number")
  
      chatbot = bots[int(choice) - 1][0]
      chatbot()
  
new_contents: # Natural Language Toolkit: Chatbots
  #
  # Copyright (C) 2001-2022 NLTK Project
  # Authors: Steven Bird <stevenbird1@gmail.com>
  # URL: <https://www.nltk.org/>
  # For license information, see LICENSE.TXT
  
  # Based on an Eliza implementation by Joe Strout <joe@strout.net>,
  # Jeff Epler <jepler@inetnebr.com> and Jez Higgins <jez@jezuk.co.uk>.
  
  """
  A class for simple chatbots.  These perform simple pattern matching on sentences
  typed by users, and respond with automatically generated sentences.
  
  These chatbots may not work using the windows command line or the
  windows IDLE GUI.
  """
  
  from nltk.chat.eliza import eliza_chat
  from nltk.chat.iesha import iesha_chat
  from nltk.chat.rude import rude_chat
  from nltk.chat.suntsu import suntsu_chat
  from nltk.chat.util import Chat
  from nltk.chat.zen import zen_chat
  
  bots = [
      (eliza_chat, "Eliza (psycho-babble)"),
      (iesha_chat, "Iesha (teen anime junky)"),
      (rude_chat, "Rude (abusive bot)"),
      (suntsu_chat, "Suntsu (Chinese sayings)"),
      (zen_chat, "Zen (gems of wisdom)"),
  ]
  
  
  def chatbots():
      print("Which chatbot would you like to talk to?")
      botcount = len(bots)
      for i in range(botcount):
          print("  %d: %s" % (i + 1, bots[i][1]))
      while True:
          choice = input(f"\nEnter a number in the range 1-{botcount}: ").strip()
          if choice.isdigit() and (int(choice) - 1) in range(botcount):
              break
          else:
              print("   Error: bad chatbot number")
  
      chatbot = bots[int(choice) - 1][0]
      chatbot()
  
subject: Use input() instead of sys.stdin.readline(), as Jupyter supports the former