"""
I'm happy with the api you provide, with a small addition:
PyAPI_FUNC(int) Py_SetAllocators(
    char api,
    void* (*malloc) (size_t size, void *data),
    void* (*realloc) (void* ptr, size_t size, void *data),
    void (*free) (void* ptr, void *data),
    void *data
    );
"""

Oops, I forgot "void *data". Yeah, each group of allocator functions (malloc, free and realloc) will get its own "data" pointer.