bpo-42528: Improve the docs of most Py*_Check{,Exact} API calls (GH-23602)
I think that none of these API calls can fail, but only few of them are
documented as such. Add the sentence "This function always succeeds" (which is
the same already used e.g. by PyNumber_Check) to all of them.diff --git a/Doc/c-api/iter.rst b/Doc/c-api/iter.rst
index 68df6f6..74fb557 100644
--- a/Doc/c-api/iter.rst
+++ b/Doc/c-api/iter.rst
@@ -9,7 +9,8 @@
.. c:function:: int PyIter_Check(PyObject *o)
- Return true if the object *o* supports the iterator protocol.
+ Return true if the object *o* supports the iterator protocol. This
+ function always succeeds.
.. c:function:: PyObject* PyIter_Next(PyObject *o)