new_contents: #!/usr/bin/python
  #-*- coding: utf-8 -*-
  import numpy as np
  import matplotlib.pyplot as plt
  
  
  x = np.linspace(0, 10, 500)
  dashes = [10, 5, 100, 5]  # 10 points on, 5 off, 100 on, 5 off
  
  fig, ax = plt.subplots()
  line1, = ax.plot(x, np.sin(x), '--', linewidth=2,
                   label='Dashes set retroactively')
  line1.set_dashes(dashes)
  
  line2, = ax.plot(x, -1 * np.sin(x), dashes=[30, 5, 10, 5],
                   label='Dashes set proactively')
  
  ax.legend(loc='lower right')
  plt.show()
subject: Add the demo.ty to test matoplib