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7.1.2 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 `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. New in version 2.4.