This fork uses uv. From the repo root:
uv sync
uv run pytest tests/
pycss itself is pure Python. The original Cython
choldate dependency is
replaced by a pure-NumPy implementation in pycss/chol.py; the original
package is vendored under vendor/choldate/ (with the build fixes from
choldate PR #8) as a
dev-only dependency so the replacement is tested against it
(tests/test_chol.py). Reference benchmarks live in benchmarks/.