Issue #1066: implement PEP 3109, 2/3 of PEP 3134.
diff --git a/Grammar/Grammar b/Grammar/Grammar
index 17a0148..6111fae 100644
--- a/Grammar/Grammar
+++ b/Grammar/Grammar
@@ -49,7 +49,7 @@
continue_stmt: 'continue'
return_stmt: 'return' [testlist]
yield_stmt: yield_expr
-raise_stmt: 'raise' [test [',' test [',' test]]]
+raise_stmt: 'raise' [test ['from' test]]
import_stmt: import_name | import_from
import_name: 'import' dotted_as_names
# note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS