code: def _create_bitstream(file_path, local_file, item_id, log_ind=None):
      
      checksum = _streaming_file_md5(file_path)
      upload_token = session.communicator.generate_upload_token(
          session.token, item_id, local_file, checksum)
  
      if upload_token != '':
          log_trace = 'Uploading bitstream from {0}'.format(file_path)
          # only need to perform the upload if we haven't uploaded before
          # in this cae, the upload token would not be empty
          session.communicator.perform_upload(
              upload_token, local_file, filepath=file_path, itemid=item_id)
      else:
          log_trace = 'Adding a bitstream link in this item to an existing ' \
                      'bitstream from {0}'.format(file_path)
  
      if log_ind is not None:
          log_trace += log_ind
      print(log_trace)
docs: Create a bitstream in the given item.
  
      :param file_path: full path to the local file
      :type file_path: string
      :param local_file: name of the local file
      :type local_file: string
      :param log_ind: (optional) any additional message to log upon creation of
          the bitstream
      :type log_ind: None | string