code: func (o *ClientOptions) SetMessageChannelDepth(s uint) *ClientOptions {
  	o.MessageChannelDepth = s
  	return o
  }
docs: // SetMessageChannelDepth sets the size of the internal queue that holds messages while the
  // client is temporairily offline, allowing the application to publish when the client is
  // reconnecting. This setting is only valid if AutoReconnect is set to true, it is otherwise
  // ignored.