code: public function process(ThingInterface $thing, $sourcePath, OptionsInterface $options = null)
      {
          $result = null;
          foreach ($this->filters as $filter) {
              if ($result === null) {
                  $result = $filter->process($thing, $sourcePath, $options);
              } else {
                  $tmp = [];
  
                  foreach ($result as $path) {
                      $tmp = array_merge($tmp, $filter->process($thing, $path, $options));
                  }
  
                  $result = $tmp;
              }
          }
  
          return $result;
      }
docs: @param ThingInterface   $thing
  @param string           $sourcePath
  @param OptionsInterface $options
  
  @return array Paths to generated files