docs: def scatterAlign(seq1, seq2, window=7):
      """
      Visually align two sequences.
      """
      d1 = defaultdict(list)
      d2 = defaultdict(list)
      for (seq, section_dict) in [(seq1, d1), (seq2, d2)]:
          for i in range(len(seq) - window):
              section = seq[i:i + window]
              section_dict[section].append(i)
      matches = set(d1).intersection(d2)
      print('%i unique matches' % len(matches))
      x = []
      y = []
      for section in matches:
          for i in d1[section]:
              for j in d2[section]:
                  x.append(i)
                  y.append(j)
      # plt.cla()  # clear any prior graph
      plt.gray()
      plt.scatter(x, y)
      plt.xlim(0, len(seq1) - window)
      plt.ylim(0, len(seq2) - window)
      plt.xlabel('length %i bp' % (len(seq1)))
      plt.ylabel('length %i bp' % (len(seq2)))
      plt.title('Dot plot using window size %i\n(allowing no mis-matches)' %
                window)
      plt.show()