new_contents: 
  # coding = utf-8
  __author__= 'liez'
  
  import random
  
  def make_number(num, length):
      str = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
      a = []
      i = 0
      while i < num:
          numstr = ''
          for j in range(length):
              numstr += random.choice(str)
          if numstr not in a: #如果没重复
              a.append(numstr)
              i += 1
              print(numstr)
  
  make_number(20,10)
  
subject: Create 0001.py