code: def process_file(self, path, dryrun):
          
          # special case - skip output file so we won't include it in result
          if path == self._output_path:
              return None
  
          # if dryrun skip and return file
          if dryrun:
              return path
  
          # concat file with output file
          with open(path, "rb") as infile:
              data = infile.read()
              self._output_file.write(data)
  
          # return processed file path
          return path
docs: Concat files and return filename.