In order to add this to the intergration tests, could you also return ```km_sub_kernel``` at the end of the function?
This will break the python_modular integration tests (since you changed something)
So you will have to re-generate the test with the generator.py file in the integration test directory (ask on IRC if unclear), and then do a shogun-data update (first the update, then update this PR with the corresponding data version)