update symbol.py for yield from grammar changes (closes #17132)
diff --git a/Lib/symbol.py b/Lib/symbol.py
index a702ed3..34143b5 100755
--- a/Lib/symbol.py
+++ b/Lib/symbol.py
@@ -91,6 +91,7 @@
 comp_if = 334
 encoding_decl = 335
 yield_expr = 336
+yield_arg = 337
 #--end constants--
 
 sym_name = {}