'Call this method in your plugin\'s identify method to normalize metadata
before putting the Metadata object into result_queue. You can of
course, use a custom algorithm suited to your metadata source.'

def clean_downloaded_metadata(self, mi):

    docase = ((mi.language == u'eng') or mi.is_null(u'language'))
    if (docase and mi.title):
        mi.title = fixcase(mi.title)
    mi.authors = fixauthors(mi.authors)
    if (mi.tags and docase):
        mi.tags = list(map(fixcase, mi.tags))
    mi.isbn = check_isbn(mi.isbn)
