codeigniter check for user session in every controller

[AdoreHim]

I have this private session in one of my controllers that checks if a user is logged in:\[code\]function _is_logged_in() { $user = $this->session->userdata('user_data'); if (!isset($user)) { return false; } else { return true; }}\[/code\]Problem is that I have more than one Controller. How can I use this function in those other controllers? Redefining the function in every Controller isn't very 'DRY'.Any ideas?