docs: 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))