Drupal block visibility PHP

//To show a block only on user pages or certain nodes

$ShowBlock = false;

$ShowBlock = ((arg(0) == 'user') && is_numeric(arg(1)) && (arg(2) == null));
 if ($ShowBlock)
    return $ShowBlock; // Is user page
   
$ShowBlock = ((arg(0) == 'node') && (arg(2) == null));
if (!$ShowBlock)
    return $ShowBlock; // Not node page
   
$ShowBlock = (arg(1)==1 || arg(1)==13926 || arg(1)==13927 || arg(1)==13928 || arg(1)==13929 || arg(1)==13930);

return $ShowBlock; // Front page or not
?>