public function enqueue($markup, array $args = [])
    {
        $notice = $args; // As notice.

        // Use `$markup` if not in `$args`.
        if ($markup && empty($notice['markup'])) {
            $notice['markup'] = $markup;
        }
        $notice = $this->normalize($notice);

        if (!$notice['markup']) {
            return; // Nothing to do.
        }
        $key     = $this->key($notice);
        $notices = $this->get();

        if ($notice['push_to_top']) {
            $this->c::arrayUnshiftAssoc($notices, $key, $notice);
        } else {
            $notices[$key] = $notice; // Default behavior.
        }
        $this->update($notices);
    }