buren/arbetsformedlingen ? reverse-engineered prompt

Build me a Ruby gem for working with the Swedish Employment Service API.

I want to be able to search job ads by keyword, fetch a single ad by id, and look up things like countries or other location related data. I also need separate clients for the different parts of the API, like the main job ads API, the ontology lookup, the taxonomy service, and the WSOccupation service.

It should feel easy to use in a normal Ruby app, with a simple client object and Ruby objects for the returned data. Please include the ability to post a job ad too, with validation on the models so bad data is caught early before sending it. A complete example for creating and posting an ad would be really helpful.

If you need to check the current API details or docs online while building it, go ahead and do that. Also add a few examples and tests so I can see how it works and know it is behaving correctly.