code: def recv(self, filename, dest_file, timeout=None):
      
      transport = DataFilesyncTransport(self.stream)
      transport.write_data('RECV', filename, timeout)
      for data_msg in transport.read_until_done('DATA', timeout):
        dest_file.write(data_msg.data)
docs: Retrieve a file from the device into the file-like dest_file.