Python 中的
None是什么？
None是一个特殊的常量。 None和False不同。 None不是0。 None不是空字符串。 None和任何其他的数据类型比较永远返回False。 None有自己的数据类型NoneType。 你可以将None复制给任何变量，但是你不能创建其他NoneType对象。
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.)
KF