docs: def getrdfdata():
  	"""Downloads Project Gutenberg RDF catalog.
  	Yields:
  		xml.etree.ElementTree.Element: An etext meta-data definition.
  	"""
  	if not os.path.exists(RDFFILES):
  		_, _ = urllib.urlretrieve(RDFURL, RDFFILES)
  	with tarfile.open(RDFFILES) as archive:
  		for tarinfo in archive:
  			yield ElementTree.parse(archive.extractfile(tarinfo))