pythonの変換暗号化アルゴリズムの例

def  translationCipher(msg,key):
   result = [""]*key
   for i in range(key):#                    
    pointer = i
    while i<len(msg):
     result[pointer]+=msg[i]
     i+=key
   return ''.join(result)

def  main():
  print translationCipher("hello,world",4)# 4            
if  __name__=="__main__":
  main()