docs: def subscriber(address,topics,callback,message_type):
      """
      Creates a subscriber binding to the given address and 
      subscribe the given topics.
      The callback is invoked for every message received.
  
          Args:
              - address: the address to bind the PUB socket to.
              - topics: the topics to subscribe
              - callback: the callback to invoke for every message. Must accept 2 variables - topic and message
              - message_type: the type of message to receive
      """
      return Subscriber(address,topics,callback,message_type)