code: func (m *AgentMDNS) poll(hosts chan *mdns.ServiceEntry) {
  	params := mdns.QueryParam{
  		Service:   mdnsName(m.discover),
  		Interface: m.iface,
  		Entries:   hosts,
  	}
  	if err := mdns.Query(&params); err != nil {
  		m.logger.Printf("[ERR] agent.mdns: Failed to poll for new hosts: %v", err)
  	}
  }
docs: // poll is invoked periodically to check for new hosts