'Open gzip compressed tar archive name for reading or writing.
Appending is not allowed.'

@classmethod
def gzopen(cls, name, mode='r', fileobj=None, compresslevel=9, **kwargs):

    if ((len(mode) > 1) or (mode not in 'rw')):
        raise ValueError("mode    must    be    'r'    or    'w'")
    try:
        import gzip
        gzip.GzipFile
    except (ImportError, AttributeError):
        raise CompressionError('gzip    module    is    not    available')
    extfileobj = (fileobj is not None)
    try:
        fileobj = gzip.GzipFile(name, (mode + 'b'), compresslevel, fileobj)
        t = cls.taropen(name, mode, fileobj, **kwargs)
    except IOError:
        if ((not extfileobj) and (fileobj is not None)):
            fileobj.close()
        if (fileobj is None):
            raise
        raise ReadError('not    a    gzip    file')
    except:
        if ((not extfileobj) and (fileobj is not None)):
            fileobj.close()
        raise
    t._extfileobj = extfileobj
    return t
