@classmethod<EOL><INDENT>def extract_master_tarball(cls):<DEDENT>
if not os.path.exists(cls.master_tarball_file):<EOL><INDENT>cls.download_grids()<EOL><DEDENT>with tarfile.open(os.path.join(ISOCHRONES, cls.master_tarball_file)) as tar:<EOL><INDENT>logging.info('<STR_LIT>'.format(cls.master_tarball_file))<EOL>tar.extractall(ISOCHRONES)<EOL><DEDENT>
Unpack tarball of tarballs