Common example files across implementations

Do we want some common example data files that are used on all the implementations? For example, common files used in the various dataset API recipes. I don't really know how often people will be bouncing between languages or comparing languages though.

Start by reviewing the existing dataset API recipes across the implementations and comparing the example data they currently use. Clarify whether shared files are needed and how they should be organized; the issue is done when the cross-language approach and required common files are agreed and documented.

Written by the indexing model from the issue text.