code: def normalize_message(message_text):
      
      for mark in PUNCTUATION_MARKS:
          message_text = message_text.replace(mark, ' ')
      # Add barier elements for not deleting middle of word
      message_text = ' ' + message_text + ' '
      for article in ARTICLES:
          message_text = message_text.replace(article, ' ')
      # Delete extra spaces
      message_text = ' '.join(message_text.split())
      # TODO: Delete bot appeals (like 'hey bot', 'hi', 'bot') if it's not
      #       the only content of message
      return message_text
docs: Remove punctuation marks, articles
      and bot appeals (like 'hey bot')
  
      :param message_text: user's message text
      :return: normalized message text