code: protected function asset($type)
      {
          $busters = $this->checkAndGetBusters();
  
          // get busters.json hash for item of this type mapped down to this type
          // only
          $bustersOfThisType = array();
          foreach ($busters as $key => $value) {
              if (strpos($key, $type) !== false) {
                  $bustersOfThisType[$key] = $value;
              }
          }
  
          $busterStrings = $this->parseTags($bustersOfThisType, $type);
  
          return implode("\n", $busterStrings);
      }
docs: abstracted single asset
  
  @param  string                   $type either 'css' or 'js'
  @throws LengthException          if the busters.json file is not found
  @throws UnderflowException       if the busters.json file contents are empty
  @throws UnexpectedValueException if the busters.json has text but is not
  valid json
  @return string