code: def open_only(func):
      
  
      @wraps(func)
      def _check(self, *args, **kwds):
          if (
              self.closed
              or self.eof_received
              or self.eof_sent
              or not self.active
          ):
              raise SSHException("Channel is not open")
          return func(self, *args, **kwds)
  
      return _check
docs: Decorator for `.Channel` methods which performs an openness check.
  
      :raises:
          `.SSHException` -- If the wrapped method is called on an unopened
          `.Channel`.