code: def web_address(self):
          
          port = self._current_web_port()
          address = self.address or '127.0.0.1'
          if port is None:
              return None
          return 'http://{0}:{1}/'.format(
              address if address and not is_boot2docker() else docker_host(),
              port)
docs: Return the url of the web server or None if not running