protected function findRole($role)
    {
        // Try to see if we have a role registered for the given
        // key so we can determine the role's inheritances.
        if (array_key_exists($role, $this->roles)) {
            return $this->roles[$role];
        }

        // If we couldn't find a registered role for the
        // given key, just return a new role object.
        return new SimpleRole($role);
    }