code: func (o *ClientOptions) SetKeepAlive(k time.Duration) *ClientOptions {
  	o.KeepAlive = int64(k / time.Second)
  	return o
  }
docs: // SetKeepAlive will set the amount of time (in seconds) that the client
  // should wait before sending a PING request to the broker. This will
  // allow the client to know that a connection has not been lost with the
  // server.