code: def download_stream(self, source, *, offset=0):
          
          return self.get_stream("RETR " + str(source), "1xx", offset=offset)
docs: :py:func:`asyncio.coroutine`
  
          Create stream for read data from `source` file.
  
          :param source: source path of file on server side
          :type source: :py:class:`str` or :py:class:`pathlib.PurePosixPath`
  
          :param offset: byte offset for stream start position
          :type offset: :py:class:`int`
  
          :rtype: :py:class:`aioftp.DataConnectionThrottleStreamIO`