生成器对象
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Generator objects are what Python uses to implement generator
iterators. They are normally created by iterating over a function that
yields values, rather than explicitly calling "PyGen_New()".

PyGenObject

   用于生成器对象的C结构体。

PyTypeObject PyGen_Type

   与生成器对象对应的类型对​​象。

int PyGen_Check(ob)

   如果 *ob* 是一个生成器对象，则返回true; *ob* 不得为 *NULL*。

int PyGen_CheckExact(ob)

   Return true if *ob*’s type is *PyGen_Type* is a generator object;
   *ob* must not be *NULL*.

PyObject* PyGen_New(PyFrameObject *frame)
    *Return value: New reference.*

   Create and return a new generator object based on the *frame*
   object. A reference to *frame* is stolen by this function. The
   parameter must not be *NULL*.
