Implement PEP 380 - 'yield from' (closes #11682)
diff --git a/Include/graminit.h b/Include/graminit.h
index e0e27f9..3ec949a 100644
--- a/Include/graminit.h
+++ b/Include/graminit.h
@@ -81,3 +81,4 @@
 #define comp_if 334
 #define encoding_decl 335
 #define yield_expr 336
+#define yield_arg 337