@NotNull
 private static List<PyGenericType> collectGenericTypes(
     @NotNull PyClass cls, @NotNull Context context) {
   boolean isGeneric = false;
   for (PyClass ancestor : cls.getAncestorClasses(context.getTypeContext())) {
     if (GENERIC_CLASSES.contains(ancestor.getQualifiedName())) {
       isGeneric = true;
       break;
     }
   }
   if (isGeneric) {
     final ArrayList<PyGenericType> results = new ArrayList<>();
     // XXX: Requires switching from stub to AST
     for (PyExpression expr : cls.getSuperClassExpressions()) {
       if (expr instanceof PySubscriptionExpression) {
         final PyExpression indexExpr = ((PySubscriptionExpression) expr).getIndexExpression();
         if (indexExpr != null) {
           for (PsiElement resolved : tryResolving(indexExpr, context.getTypeContext())) {
             final PyGenericType genericType = getGenericType(resolved, context);
             if (genericType != null) {
               results.add(genericType);
             }
           }
         }
       }
     }
     return results;
   }
   return Collections.emptyList();
 }