The None Object
Note that the PyTypeObject for None is not directly exposed in the
Python/C API.  Since None is a singleton, testing for object identity (using
== in C) is sufficient. There is no PyNone_Check() function for the
same reason.
- 
PyObject *Py_None
 
- The Python - Noneobject, denoting lack of value.  This object has no methods.
It needs to be treated just like any other object with respect to reference
counts.
 
- 
Py_RETURN_NONE
 
- Properly handle returning - Py_Nonefrom within a C function (that is,
increment the reference count of- Noneand return it.)