def _widening_points(self, function_address):
        try:
            new_function = self.kb.functions[function_address]
        except KeyError:
            return [ ]
        if function_address not in self._function_widening_points:
            if not new_function.normalized:
                new_function.normalize()
            widening_points = CFGUtils.find_widening_points(function_address, new_function.endpoints,
                                                                    new_function.graph)
            self._function_widening_points[function_address] = widening_points
        return self._function_widening_points[function_address]