code: public function overlayMessage($compare, $dumper)
      {
          $this->dumper = $dumper;
  
          return sprintf($this->message, $this->testMessage($compare));
      }
docs: Overlays the generated message onto the stored user message.
  An additional message can be interjected.
  
  @param mixed $compare        Comparison value.
  @param SimpleDumper $dumper  For formatting the results.
  
  @return string               Description of success or failure.