This is a follow up to #57 (comment)
I think what I'd suggest we do is to add a new use-cases folder, and in that folder create required-options with index.js, index.d.ts and index.test-d.ts files.
In /use-cases/required-options/index.d.ts we would define a required option by extending the Base.Options interface and then add tests to index.test-d.ts to make sure the types work correctly with the new Base(options) constructor and with .defaults(options) calls