图片中老是出现这个问题，我将中间的变量改了之后，就可可以用了这是为什么？

#password.py
pwd =input('What is your password?')
if pwd == 12345: #note use of == instead of =
    print('Loging on....')
else:
    print('Incorrect password')
print('All done')

如果我将“pwd == 12345”改成了“pwd == ‘apple’”之后就会出现下面的问题

Traceback (most recent call last):
  File "C:/python/password.py", line 2, in <module>
    pwd =input('What is your password?')
  File "<string>", line 1, in <module>
NameError: name 'apple' is not defined

这是什么原因，是需要我自己设置一个文件来定义name中有哪些名字吗？还是与版本有关?我用的版本是Python2.7.9