问为什么下面的程序无法将摩尔斯电码转换为英语原文？

code=["._","_...","_._.","_..",".",".._.","__.","....","..",".___","_._","._..","__","_.","___",".__.","__._","._.","...","_",".._","..._",".__","_.._","_.__","__.."]

message=input("请输入电报：")

message+=""

chars=""

output=""

for letter in message:

if letter!="":

chars=chars+letter

else:

for index in range(26):

if code[index]==chars:

output+=chr(ord('A')+index)

chars=""

print("英语原文是：",output)