Minor C API documentation improvements. (GH-17696)
The added parentheses around the PyIter_Next assignment suppress the following warning which gcc throws without:
```
warning: using the result of an assignment as a condition without parentheses [-Wparentheses]
```
The other change is a typo fix
diff --git a/Doc/includes/custom.c b/Doc/includes/custom.c
index bda32e2..f361baf 100644
--- a/Doc/includes/custom.c
+++ b/Doc/includes/custom.c
@@ -37,7 +37,7 @@
Py_INCREF(&CustomType);
if (PyModule_AddObject(m, "Custom", (PyObject *) &CustomType) < 0) {
Py_DECREF(&CustomType);
- PY_DECREF(m);
+ Py_DECREF(m);
return NULL;
}