Remove private _PyThreadState and _PyInterpreterState C API functions: move them to the internal C API (pycore_pystate.h and pycore_interp.h). Don't export most of these functions anymore, but still export functions used by tests. Remove _PyThreadState_Prealloc() and _PyThreadState_Init() from the C API, but keep it in the stable API.
The Python C API ================ The C API is divided into these sections: 1. ``Include/``: Limited API 2. ``Include/cpython/``: CPython implementation details 3. ``Include/cpython/``, names with the ``PyUnstable_`` prefix: API that can change between minor releases 4. ``Include/internal/``, and any name with ``_`` prefix: The internal API Information on changing the C API is available `in the developer guide`_ .. _in the developer guide: https://devguide.python.org/c-api/