give a better error message when deleting ()
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index c1027b1..26d78ad 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -462,6 +462,12 @@
   File "<doctest test.test_syntax[49]>", line 1
 SyntaxError: keyword argument repeated
 
+>>> del ()
+Traceback (most recent call last):
+   ...
+  File "<doctest test.test_syntax[50]>", line 1
+SyntaxError: can't delete ()
+
 """
 
 import re