bpo-39573: Clean up modules and headers to use Py_IS_TYPE() function (GH-18521)

diff --git a/Modules/parsermodule.c b/Modules/parsermodule.c
index f00329b..24b0ffb 100644
--- a/Modules/parsermodule.c
+++ b/Modules/parsermodule.c
@@ -256,7 +256,7 @@
 
 
 /* PyST_Type isn't subclassable, so just check ob_type */
-#define PyST_Object_Check(v) (Py_TYPE(v) == &PyST_Type)
+#define PyST_Object_Check(v) Py_IS_TYPE(v, &PyST_Type)
 
 static int
 parser_compare_nodes(node *left, node *right)