import re
import unicodedata


def slugify(string):
    """
    Slugify unicode string.

    Example:
        >>> slugify("Hélló Wörld")
        "hello-world"
    """
    if not string:
        return ''
    return re.sub(r'[-\s]+', '-', re.sub(r'[^\w\s-]', '', unicodedata.normalize('NFKD', string)).strip().lower())