_slugify_strip_re = re.compile(r'[^\w\s-]')
_slugify_hyphenate_re = re.compile(r'[-\s]+')
def _slugify(value):
    """
    Normalizes string, converts to lowercase, removes non-alpha characters,
    and converts spaces to hyphens.
    
    From Django's "django/template/defaultfilters.py".
    """
    import unicodedata
    if not isinstance(value, unicode):
        value = unicode(value)
    value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore')
    value = unicode(_slugify_strip_re.sub('', value).strip().lower())
    return _slugify_hyphenate_re.sub('-', value)