This week, I am finishing my final PR to fix the Coiteration algorithm: https://github.com/hameerabbasi/xsparse/pull/31.
This will enable coiterations over levels that are nested within other levels. As such, we can define multiple Coiterate objects that co-iterate over each dimension respectively.
With this, the ground-work will be laid to very easily implement the MergeLattice Coiterator, which is just an abstraction on top of this idea of calling multiple coiterators.
The final PR now shows a unit-test that Co-iterates over two sets of nested levels, which each together define a CSR matrix. It is done with a conjunctive merge, so the unit-test defines how the API must be specifically defined. There were a few errors that I ran into that were hard to debug, but it turns out they were consequences of how I was leveraging the Coiterate API, which is slightly unforgiving right now.