code: func occupyServiceCIDR(set *cidrset.CidrSet, clusterCIDR, serviceCIDR *net.IPNet) error {
  	if clusterCIDR.Contains(serviceCIDR.IP) || serviceCIDR.Contains(clusterCIDR.IP) {
  		if err := set.Occupy(serviceCIDR); err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // occupyServiceCIDR removes the service CIDR range from the cluster CIDR if it
  // intersects.