input: Write a function to implement a chatbot that can provide customer support in a restaurant. The function should read a user's question from a file named 'random_user_question.txt', choose a random response from a list of possible responses, and print the response to the user. The function should have the following signature: def chatbot_restaurant(filename: str) -> None.  
  assert chatbot_restaurant('random_user_question.txt')==None  
  assert chatbot_restaurant('random_user_question.txt')==None  
  assert chatbot_restaurant('random_user_question.txt')==None  
  assert chatbot_restaurant('random_user_question.txt')==None  
  assert chatbot_restaurant('random_user_question.txt')==None
output: def chatbot_restaurant(filename: str) -> None:
      import random
      responses = ["We're glad to help!", "Please visit our website for more details.", "Our customer service is available 24/7.", "Thank you for your question, we'll get back to you shortly."]
      with open(filename, 'r') as file:
          question = file.read().strip()
      print(random.choice(responses))