/**
* Do the actual work. All child classes will need to implement this
*
- * @return bool|null True for success, false for failure. Not returning
+ * @return bool|null|void True for success, false for failure. Not returning
* a value, or returning null, is also interpreted as success. Returning
* false for failure will cause doMaintenance.php to exit the process
* with a non-zero exit status.