def _tarjan(self, function, order, stack, orders, lowlinks, visited):
        """Tarjan's strongly connected components algorithm.

        See also:
        - http://en.wikipedia.org/wiki/Tarjan's_strongly_connected_components_algorithm
        """

        visited.add(function)
        orders[function] = order
        lowlinks[function] = order
        order += 1
        pos = len(stack)
        stack.append(function)
        for call in function.calls.values():
            callee = self.functions[call.callee_id]
            # TODO: use a set to optimize lookup
            if callee not in orders:
                order = self._tarjan(callee, order, stack, orders, lowlinks, visited)
                lowlinks[function] = min(lowlinks[function], lowlinks[callee])
            elif callee in stack:
                lowlinks[function] = min(lowlinks[function], orders[callee])
        if lowlinks[function] == orders[function]:
            # Strongly connected component found
            members = stack[pos:]
            del stack[pos:]
            if len(members) > 1:
                cycle = Cycle()
                for member in members:
                    cycle.add_function(member)
        return order
Tarjan's strongly connected components algorithm.

        See also:
        - http://en.wikipedia.org/wiki/Tarjan's_strongly_connected_components_algorithm
        
recipes/Python/578138_gprof2dotpy/recipe-578138.py