code: def open_channel(self):
          
          if self._closing:
              raise ConnectionClosed("Closed by application")
          if self.closed.done():
              raise self.closed.exception()
  
          channel = yield from self.channel_factory.open()
          return channel
docs: Open a new channel on this connection.
  
          This method is a :ref:`coroutine <coroutine>`.
  
          :return: The new :class:`Channel` object.