The None Object — Python 3.6.6 documentation

# 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 (that is, increment the reference count of `None` and return it.)