code: func (c *connection) Close() error {
  	c.mu.Lock()
  	if c.stopErr == nil {
  		c.stopErr = ErrClosed
  		close(c.stop)
  	}
  	c.mu.Unlock()
  	return c.rw.Close()
  }
docs: // Close close underlying transport connection and cancel all pending response
  // waiters.