new_contents: import re
  import time
  import random
  random.seed(int(time.time()))
  length = 100
  keyinit = "".join([chr(random.randint(97,122)) for i in range(0,100)])
  
  class Cipher(object):
      def __init__(self, key=keyinit):
          if not key.isalpha():
              raise ValueError
          if not key.islower():
              raise ValueError
          numkey = []
          for item in key:
              numkey.append(ord(item)-97)
          #self.caesar = Caesar(numkey)
          self.key = key
          self.jump = numkey
  
      def encode(self, strs):
          plain_code = re.sub("[^a-z]","",strs.lower())
          ret=[]
          for idx, item in enumerate(plain_code):
              jump_idx = idx%len(self.jump)
              ascii = ord(item)+self.jump[jump_idx]
              if ascii > 122:
                  ascii -= 26
              ret.append(chr(ascii))
          return "".join(ret)
  
      def decode(self, strs):
          ret = []
          for idx,item in enumerate(strs):
              jump_idx = idx%len(self.jump)
              ascii = ord(item)-self.jump[jump_idx]
              if ascii < 97:
                  ascii += 26
              ret.append(chr(ascii))
          return "".join(ret)
  
  
  
  
  
  
  class Caesar(Cipher):
      def __init__(self):
          super(Caesar,self).__init__('d')
  
subject: Add better solution for simple cipher