Start creating py__getitem__.

jedi/evaluate/analysis.py

@@ -20,6 +20,7 @@ CODES = {
     'type-error-operation': (11, TypeError, None),
     'type-error-not-iterable': (12, TypeError, None),
     'type-error-isinstance': (13, TypeError, None),
+    'type-error-not-subscriptable': (13, TypeError, None),
 }