code: def start(self):
          
          if self._using_filename:
              with open(self.file, 'rb') as file:
                  return self.request_upload_token(file)
          else:
              return self.request_upload_token(self.file)
docs: Kick off uploading process. Handles open/closing file if a path
          is passed.
  
          :calls: request_upload_token
          :returns: True if the file uploaded successfully, False \
              otherwise, and the JSON response from the API.
          :rtype: tuple