Service instructions for a custom integration?

I want to add a service to a simple integration I wrote that takes two strings and calls a function with them as inputs.

I have a light integration based on the awesome light which is not async. I’ve found this service example, but it does not take any inputs: example-custom-config/custom_components/expose_service_sync at master · home-assistant/example-custom-config · GitHub .

The service example in the normal documentation is for asych, and does not seem to work for my integration. Integration Services | Home Assistant Developer Docs

Any tips on how to get started?