Write an internal golang package that 

 - Follows the Uber Golang Style Guide (https://github.com/uber-go/guide/blob/master/style.md)
 - Uses the `cloudflare-go` library (https://pkg.go.dev/github.com/cloudflare/cloudflare-go) 
 - Uses a New constructor with api token as the only required parameter
 - Sets via lookup by Name the ZoneID via a functional option and/or a method
 - Sets the DNS Record ID by name for a subdomain via a functional option and/or a method
 - Sets the DNS Record (upsert) to an A record with a provided IP address