code: func (c *Client) SetBeforeReconnectHandler(h handler) {
  	c.Lock()
  	defer c.Unlock()
  	c.beforeReconnect = h
  }
docs: // SetBeforeReconnectHandler registers a handler that will be called
  // before retrying to reconnect to the event server. This allows for
  // custom code to be executed for a particular event client implementation.