We separate the h3-py tests into two groups, organized by subfolder.
We do this because we expect 100% coverage on the library tests, but are still working through getting full coverage on the Cython tests.
The tests in this folder are for the main h3-py Python API for folks
who are using the pure-Python library functionality.
The tests in this folder are for the advanced Cython API, that allows
for other Cython packages or scripts to use the Cython code provided
by the h3-py internals.
Note that the "Cython API" of h3-py is not currently externally supported.