hg-cpython-0.0.1 doesn't have any documentation.
Python bindings of hg-core objects using the cpython crate.
Once compiled, the resulting single shared library object can be placed in
the mercurial package directly as rustext.so or rustext.dll.
It holds several modules, so that from the point of view of Python,
it behaves as the cext package.
Example:
>>> from mercurial.rustext import ancestor
>>> ancestor.__doc__
'Generic DAG ancestor algorithms - Rust implementation'