def _source_urls(album, sources=SOURCES_ALL):
 for s in sources:
  urls = ART_FUNCS[s](album)
  for url in urls:
   (yield url)

def _source_urls ( album , sources = SOURCES_ALL ) : for s in sources : urls = ART_FUNCS [ s ] ( album ) for url in urls : ( yield url )
generate possible source urls for an albums art .