def visit_subscript(self, node):
        """ Look for indexing exceptions. """
        try:
            for inferred in node.value.infer():
                if not isinstance(inferred, astroid.Instance):
                    continue
                if utils.inherit_from_std_ex(inferred):
                    self.add_message("indexing-exception", node=node)
        except astroid.InferenceError:
            return