def levenshtein(s, t):
    """
    Computes the levenschtein distance between two strings of text
    This is borrowed code and has been checked, but stay careful
    :param s: first string of text
    :param t: second string of text
    :return: a distance measure, not normalized
    """
    if s == "":
        return len(t)
    if t == "":
        return len(s)
    if s[-1] == t[-1]:
        cost = 0
    else:
        cost = 1
    res = min([levenshtein(s[:-1], t) + 1,
               levenshtein(s, t[:-1]) + 1,
               levenshtein(s[:-1], t[:-1]) + cost])
    return res