docs: def cancel(self, msg='', exc_type=CancelledError):
          """Cancels the TransferFuture
             :param msg: The message to attach to the cancellation
             :param exc_type: The type of exception to set for the cancellation
          """
          _ret = False
          if not self.is_done():
              self.notify_cancelled(msg, True)
              _ret = True
  
          return _ret