Iterator Protocol
*****************

There are two functions specifically for working with iterators.

int PyIter_Check(PyObject *o)
    * Parte del ABI Stabile dalla versione 3.8.*

   Return non-zero if the object *o* can be safely passed to
   "PyIter_Next()", and "0" otherwise.  This function always succeeds.

int PyAIter_Check(PyObject *o)
    * Parte del ABI Stabile dalla versione 3.10.*

   Return non-zero if the object *o* provides the "AsyncIterator"
   protocol, and "0" otherwise.  This function always succeeds.

   Added in version 3.10.

PyObject *PyIter_Next(PyObject *o)
    *Valore di ritorno: Nuovo riferimento.** Parte del ABI Stabile.*

   Return the next value from the iterator *o*.  The object must be an
   iterator according to "PyIter_Check()" (it is up to the caller to
   check this). If there are no remaining values, returns "NULL" with
   no exception set. If an error occurs while retrieving the item,
   returns "NULL" and passes along the exception.

To write a loop which iterates over an iterator, the C code should
look something like this:

   PyObject *iterator = PyObject_GetIter(obj);
   PyObject *item;

   if (iterator == NULL) {
       /* propagate error */
   }

   while ((item = PyIter_Next(iterator))) {
       /* do something with item */
       ...
       /* release reference when done */
       Py_DECREF(item);
   }

   Py_DECREF(iterator);

   if (PyErr_Occurred()) {
       /* propagate error */
   }
   else {
       /* continue doing useful work */
   }

type PySendResult

   The enum value used to represent different results of
   "PyIter_Send()".

   Added in version 3.10.

PySendResult PyIter_Send(PyObject *iter, PyObject *arg, PyObject **presult)
    * Parte del ABI Stabile dalla versione 3.10.*

   Sends the *arg* value into the iterator *iter*. Returns:

   * "PYGEN_RETURN" if iterator returns. Return value is returned via
     *presult*.

   * "PYGEN_NEXT" if iterator yields. Yielded value is returned via
     *presult*.

   * "PYGEN_ERROR" if iterator has raised and exception. *presult* is
     set to "NULL".

   Added in version 3.10.
