new_contents: class BaseChatBot(object):
      def respond(self, utext):
          return 'Say Something'
  
  class EchoBot(BaseChatBot):
      def respond(self, utext):
          print utext
          return None
  
  class RandomBot(BaseChatBot):
      choices = ['HeHe','let me think','Er...','Yes, you are right']
  
      def __init__(self, *args, **kwargs):
          default=self.choices
          self.choices=kwargs.pop('choices',default)
          super(RandomBot, self).__init__(*args, **kwargs)
          
      def respond(self, utext):
          import random
          return random.choice(self.choices)
  
  
subject: add chatbot.py