it looks like it's only used in two other places: [ListMembersOptions](https://github.com/google/go-github/blob/48b5b24e6455439db09161223b150305f03bbf71/github/orgs_members.go#L15) and [ReferenceListOptions](https://github.com/google/go-github/blob/48b5b24e6455439db09161223b150305f03bbf71/github/git_refs.go#L68), and in both of those cases it's used to trigger a different request URL.  So this feature certainly isn't used often, but is nice to have when you need it :)