SF patch 1631942 by Collin Winter:

(a) "except E, V" -> "except E as V"
(b) V is now limited to a simple name (local variable)
(c) V is now deleted at the end of the except block

Lib/idlelib/ClassBrowser.py

@@ -94,7 +94,7 @@ def listclasses(self):
             return []
         try:
             dict = pyclbr.readmodule_ex(name, [dir] + sys.path)
-        except ImportError, msg:
+        except ImportError as msg:
             return []
         items = []
         self.classes = {}