code: func getMatchingGlobalIP(addrs []net.Addr, family AddressFamily) (net.IP, error) {
  	if len(addrs) > 0 {
  		for i := range addrs {
  			klog.V(4).Infof("Checking addr  %s.", addrs[i].String())
  			ip, _, err := net.ParseCIDR(addrs[i].String())
  			if err != nil {
  				return nil, err
  			}
  			if memberOf(ip, family) {
  				if ip.IsGlobalUnicast() {
  					klog.V(4).Infof("IP found %v", ip)
  					return ip, nil
  				} else {
  					klog.V(4).Infof("Non-global unicast address found %v", ip)
  				}
  			} else {
  				klog.V(4).Infof("%v is not an IPv%d address", ip, int(family))
  			}
  
  		}
  	}
  	return nil, nil
  }
docs: // getMatchingGlobalIP returns the first valid global unicast address of the given
  // 'family' from the list of 'addrs'.