Compute the Levenshtein distance between 2 strings, which
    is the minimum number of operations required to perform on a string to
    get another one.

    code taken from https://en.wikibooks.org

    :param basestring s:
    :param basestring t:
    :rtype: int

def levenshtein(s, t):
    """ Compute the Levenshtein distance between 2 strings, which
    is the minimum number of operations required to perform on a string to
    get another one.

    code taken from https://en.wikibooks.org

    :param basestring s:
    :param basestring t:
    :rtype: int
    """
    ''' From Wikipedia article; Iterative with two matrix rows. '''
    if s == t:
        return 0
    elif len(s) == 0:
        return len(t)
    elif len(t) == 0:
        return len(s)
    v0 = [None] * (len(t) + 1)
    v1 = [None] * (len(t) + 1)
    for i in range(len(v0)):
        v0[i] = i
    for i in range(len(s)):
        v1[0] = i + 1
        for j in range(len(t)):
            cost = 0 if s[i] == t[j] else 1
            v1[j + 1] = min(v1[j] + 1, v0[j + 1] + 1, v0[j] + cost)
        for j in range(len(v0)):
            v0[j] = v1[j]

    return v1[len(t)]