public function is(string $page = ''): bool
    {
        if (!$this->Wp->is_admin) {
            return false; // Not applicable.
        } elseif (!($current = $this->current())) {
            return false; // Nope.
        }
        if (!$page) {
            return true; // Simple check.
        }
        if ($page[0] === '/') {
            $regex = $page; // Treat as regex.
        } else {
            $regex = '/^'.$this->c::wregxFrag($page, '-').'$/ui';
        }
        return (bool) preg_match($regex, $current);
    }