docs: def ngfileupload_partfactory(part_number=None, content_length=None,
                               uploaded_file=None):
      """Part factory for ng-file-upload.
  
      :param part_number: The part number. (Default: ``None``)
      :param content_length: The content length. (Default: ``None``)
      :param uploaded_file: The upload request. (Default: ``None``)
      :returns: The content length, part number, stream, HTTP Content-Type
          header.
      """
      return content_length, part_number, uploaded_file.stream, \
          uploaded_file.headers.get('Content-Type'), None, None