added PyTuple_GET_SIZE macro
diff --git a/Include/tupleobject.h b/Include/tupleobject.h
index f5a7fa5..506f965 100644
--- a/Include/tupleobject.h
+++ b/Include/tupleobject.h
@@ -69,6 +69,7 @@
 
 /* Macro, trading safety for speed */
 #define PyTuple_GET_ITEM(op, i) (((PyTupleObject *)(op))->ob_item[i])
+#define PyTuple_GET_SIZE(op)    (((PyTupleObject *)(op))->ob_size)
 
 /* Macro, *only* to be used to fill in brand new tuples */
 #define PyTuple_SET_ITEM(op, i, v) (((PyTupleObject *)(op))->ob_item[i] = v)