Python .parameterize equivalent to Rails .parameterize

import re
import unicodedata

def parameterize(string_to_clean, sep = '-'):
    parameterized_string = unicodedata.normalize('NFKD', string_to_clean).encode('ASCII', 'ignore').decode()
    parameterized_string = re.sub("[^a-zA-Z0-9\-_]+", sep, parameterized_string)

    if sep is not None and sep is not '':
        parameterized_string = re.sub('/#{re_sep}{2,}', sep, parameterized_string)
        parameterized_string = re.sub('^#{re_sep}|#{re_sep}$', sep, parameterized_string, re.I)

    return parameterized_string.lower()