/**
  * Log a message using the converter's logging mechanism
  *
  * @param string $message message text
  * @param int $level message level {@example backup::LOG_WARNING}
  * @param null|mixed $a additional information
  * @param null|int $depth the message depth
  * @param bool $display whether the message should be sent to the output, too
  */
 public function log($message, $level, $a = null, $depth = null, $display = false)
 {
     $this->converter->log($message, $level, $a, $depth, $display);
 }