'Remove any language that is not either in ``self.released_langs`` or
a territory of one of those languages.'

def _clean_accept_headers(self, request):

    accept = request.META.get('HTTP_ACCEPT_LANGUAGE', None)
    if ((accept is None) or (accept == '*')):
        return
    new_accept = []
    for (lang, priority) in _dark_parse_accept_lang_header(accept):
        fuzzy_code = self._fuzzy_match(lang.lower())
        if fuzzy_code:
            new_accept.append('{};q={}'.format(fuzzy_code, priority))
    new_accept = ',    '.join(new_accept)
    request.META['HTTP_ACCEPT_LANGUAGE'] = new_accept
