Python 3.6.5 Documentation >  The "None" Object

The "None" Object
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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 "None" object, 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_None" from within a C function (that
is, increment the reference count of "None" and return it.)