If *fileobj* is specified, it is used as an alternative to a :term:`file object`
opened in binary mode for *name*. It is supposed to be at position 0.
+ For modes ``'w:gz'``, ``'r:gz'``, ``'w:bz2'``, ``'r:bz2'``, :func:`tarfile.open`
+ accepts the keyword argument *compresslevel* to specify the compression level of
+ the file.
+
For special purposes, there is a second format for *mode*:
``'filemode|[compression]'``. :func:`tarfile.open` will return a :class:`TarFile`
object that processes its data as a stream of blocks. No random seeking will