'Download an archive to a file object.
:type output_file: file
:param output_file: The file object where the archive
contents will be saved.
:type chunk_size: int
:param chunk_size: The chunk size to use when downloading
the archive.
:type verify_hashes: bool
:param verify_hashes: Indicates whether or not to verify
the tree hashes for each downloaded chunk.'

def download_to_fileobj(self, output_file, chunk_size=DefaultPartSize, verify_hashes=True, retry_exceptions=(socket.error,)):

    num_chunks = self._calc_num_chunks(chunk_size)
    self._download_to_fileob(output_file, num_chunks, chunk_size, verify_hashes, retry_exceptions)
