code: def download_file(self, f):
          
          #  os.chdir(self.directory)
          #  log.info('f=%s' % f)
          oldpwd = os.getcwd()
          try:
              os.chdir(self.directory)
              if is_local_filename(f.url):
                  f.local_filename = abspath(f.url)
              else:
                  if f.local_filename:
                      log.debug("Already downloaded: %s", f.local_filename)
                  else:
                      f.local_filename = self.download_url(f.url, basename='%s/%s' % (f.fileGrp, f.ID))
          finally:
              os.chdir(oldpwd)
  
          #  print(f)
          return f
docs: Download a :py:mod:`ocrd.model.ocrd_file.OcrdFile` to the workspace.