function my_tags($text = null) {
  $text = preg_replace('/\[b\](.*?)\[\/b\]/s', '<b>$1</b>', $text);
  $text = preg_replace('/\[i\](.*?)\[\/i\]/s', '<i>$1</i>', $text);
  $text = preg_replace('/\[u\](.*?)\[\/u\]/s', '<u>$1</u>', $text);
  $text = preg_replace('/\[ul\]/s', '<ul>', $text);
  $text = preg_replace('/\[\/ul\]/s', '</ul>', $text);
  $text = preg_replace('/\[li\](.*?)\[\/li\]/s', '<li>$1</li>', $text);
  $text = preg_replace('/\[h1\](.*?)\[\/h1\]/s', '<h1>$1</h1>', $text);
  $text = preg_replace('/\[h2\](.*?)\[\/h2\]/s', '<h2>$1</h2>', $text);
  $text = preg_replace('/\[h3\](.*?)\[\/h3\]/s', '<h3>$1</h3>', $text);
  $text = preg_replace('/\[center\](.*?)\[\/center\]/s', '<div class="position_center">$1</div>', $text);
  $text = preg_replace('/\[left\](.*?)\[\/left\]/s', '<div class="position_left">$1</div>', $text);
  $text = preg_replace('/\[right\](.*?)\[\/right\]/s', '<div class="position_right">$1</div>', $text);
  $text = preg_replace('/\[blockquote\](.*?)\[\/blockquote\]/s', '<blockquote>$1</blockquote>', $text);
  $text = preg_replace('/\[url=(.*?)\](.*?)\[\/url\]/s', '<a href="$1" target="_blank">$2</a>', $text);
  $text = preg_replace('/\[img\](.*?)\[\/img\]/s', '<img src="$1">', $text);
  $text = preg_replace('/\[\^\](.*?)\[\/\^\]/s', '<div class="chat_li"><div class="chat_li_point"></div>$1</div>', $text);
 
  return $text;
}