annotate CONTRIBUTING @ 30106:cb3048746dae

dirs: port PyInt code to work on Python 3

PyIntObject no longer exists in Python 3. Instead, there is
PyLongObject.

Furthermore, PyInt_AS_LONG is a macro referencing a struct member.
PyInt_AS_LONG doesn't exist in Python 3 and PyLong_AS_LONG is a
#define for PyLong_AsLong, which is a function. So assigning to the
return value of PyLong_AS_LONG doesn't work.

This patch introduces a macro for obtaining the value of an
integer-like type that works on Python 2 and Python 3. On
Python 3, we access the struct field of the underlying
PyLongObjet directly, without overflow checking. This is
essentially the same as what Python 2 was doing except using a
PyLong instead of a PyInt.

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