input: Write a python function to train a chatbot with given corpus files and get a response.
  assert get_chatbot_response("Hello, how are you today?") is not None
  assert get_chatbot_response("What is your name?") is not None
output: from chatterbot import ChatBot
  from chatterbot.trainers import ListTrainer
  
  chatbot = ChatBot('MyChatBot')
  
  def train_chatbot(corpus_files):
      trainer = ListTrainer(chatbot)
      for corpus_file in corpus_files:
          with open(corpus_file, 'r') as file:
              conversations = file.readlines()
              trainer.train(conversations)
  
  def get_chatbot_response(message):
      response = chatbot.get_response(message)
      return response.text