* Cleans up HTML, removes dangerous tags and attributes, and
* removes HTML comments
* @param string $text
- * @param callable $processCallback Callback to do any variable or parameter
+ * @param callable|null $processCallback Callback to do any variable or parameter
* replacements in HTML attribute values
* @param array|bool $args Arguments for the processing callback
* @param array $extratags For any extra tags to include
* @param array $removetags For any tags (default or extra) to exclude
- * @param callable $warnCallback (Deprecated) Callback allowing the
+ * @param callable|null $warnCallback (Deprecated) Callback allowing the
* addition of a tracking category when bad input is encountered.
* DO NOT ADD NEW PARAMETERS AFTER $warnCallback, since it will be
* removed shortly.