code: def _write_output_manifest(self, manifest, filestore_root):
          
          output = os.path.basename(manifest)
          fieldnames, source_manifest = self._parse_manifest(manifest)
          if 'file_path' not in fieldnames:
              fieldnames.append('file_path')
          with atomic_write(output, overwrite=True) as f:
              delimiter = b'\t' if USING_PYTHON2 else '\t'
              writer = csv.DictWriter(f, fieldnames, delimiter=delimiter, quoting=csv.QUOTE_NONE)
              writer.writeheader()
              for row in source_manifest:
                  row['file_path'] = self._file_path(row['file_sha256'], filestore_root)
                  writer.writerow(row)
              if os.path.isfile(output):
                  logger.warning('Overwriting manifest %s', output)
          logger.info('Rewrote manifest %s with additional column containing path to downloaded files.', output)
docs: Adds the file path column to the manifest and writes the copy to the current directory. If the original manifest
          is in the current directory it is overwritten with a warning.