Calculate the Hamming distance between two strings. From Wikipedia article: Iterative with two matrix rows.

    :param s: string 1
    :type s: str
    :param t: string 2
    :type s: str
    :return: Hamming distance
    :rtype: float

def hamming(s, t):
    """
    Calculate the Hamming distance between two strings. From Wikipedia article: Iterative with two matrix rows.

    :param s: string 1
    :type s: str
    :param t: string 2
    :type s: str
    :return: Hamming distance
    :rtype: float
    """
    if len(s) != len(t):
        raise ValueError('Hamming distance needs strings of equal length.')
    return sum(s_ != t_ for s_, t_ in zip(s, t))