Maintained repositories I can use as a good example for setting up CI (for C++ and Python build/test, no web)

I’m interested in example projects that are using GitLab CI with C++/Python build/test so I can read some sources and see how various things work, like, building with multiple compilers, integration testing C++ with Python, and (believe it or not) getting “badges” to show up in the README.md. Also - I’d be interested in external integrations, e.g., with a static analysis cloud service.

The documentation is fine, but as a newbie to CI I’d like to study (and copy) some complete, worked, examples.