code: func subnetsInCIDR(subnets []*compute.Subnetwork, cidr *net.IPNet) ([]*compute.Subnetwork, error) {
  	var res []*compute.Subnetwork
  	for _, subnet := range subnets {
  		_, subnetRange, err := net.ParseCIDR(subnet.IpCidrRange)
  		if err != nil {
  			return nil, fmt.Errorf("unable to parse CIDR %q for subnet %q: %v", subnet.IpCidrRange, subnet.Name, err)
  		}
  		if containsCIDR(cidr, subnetRange) {
  			res = append(res, subnet)
  		}
  	}
  	return res, nil
  }
docs: // subnetsInCIDR takes a list of subnets for a single region and
  // returns subnets which exists in the specified CIDR range.