API functions not working as expected

[Kirk McDonald]

... for reasons that are obvious in retrospect. Specifically, I am 
talking about the PyNumber_InPlace* family of functions. For example, 
the docs for InPlaceAdd say:

PyObject* PyNumber_InPlaceAdd(PyObject *o1, PyObject *o2)
     Return value: New reference.
     Returns the result of adding o1 and o2, or NULL on failure. The 
operation is done in-place when o1 supports it. This is the equivalent 
of the Python statement "o1 += o2".

But, of course, numbers are immutable. None of them support in-place 
addition. This is not the same as o1 += o2, as o1 is not actually 
changed when using this function.

Am I missing something here? Is there, in fact, no point to these 
InPlace* functions?

-Kirk McDonald