new_contents: #61.题目：打印出杨辉三角形（要求打印出10行如下图）。　　
  #利用生成器解决
  
  def triangle():
      x = [1]
      while True:
          yield x
          #zip: 添加0组成元组
          x = [sum(i) for i in zip([0]+x, x+[0])]
  
  num = 0
  for x in triangle():
      print(x)
      num += 1
      if num == 10:
          break
  
  #62.题目：查找字符串。
  
  str1 = 'abcdedf'
  str2 = 'ded'
  
  print('The find index is %d ' % str1.find(str2))
  
  #63.题目：画椭圆。　
  
  from tkinter import *
  
  def draw_oval():
      x = 360
      y = 160
      top = y-30
      bottom = y-30
  
      canvas = Canvas(width=400, height=600, bg='white')
  
      for i in range(20):
          canvas.create_oval(250-top, 250-bottom, 250+top, 250+bottom)
          top -= 5
          bottom += 5
      canvas.pack()
      mainloop()
  
  draw_oval()
subject: add the 61th-63th