make YieldFrom its own distinct from Yield (closes #13780)
diff --git a/Parser/Python.asdl b/Parser/Python.asdl
index 8ae4e59..876c175 100644
--- a/Parser/Python.asdl
+++ b/Parser/Python.asdl
@@ -59,7 +59,8 @@
| DictComp(expr key, expr value, comprehension* generators)
| GeneratorExp(expr elt, comprehension* generators)
-- the grammar constrains where yield expressions can occur
- | Yield(int is_from, expr? value)
+ | Yield(expr? value)
+ | YieldFrom(expr? value)
-- need sequences for compare to distinguish between
-- x < 4 < 3 and (x < 4) < 3
| Compare(expr left, cmpop* ops, expr* comparators)