code: func getVIPs(svcs []vip) []string {
  	result := []string{}
  	for _, svc := range svcs {
  		result = appendIfMissing(result, svc.IP)
  	}
  
  	return result
  }
docs: // getVIPs returns a list of the virtual IP addresses to be used in keepalived
  // without duplicates (a service can use more than one port)