python - How to deal with IndentationError? -

i following error:

file "imp.py", line 55     key = key()       ^ indentationerror: expected indented block 

with following code:

# caesar cipher  max_key_size = 26  def getmode():     while true:         print('do wish encrypt or decrypt or brute force message?')         mode = raw_input().lower()         if mode in 'encrypt e decrypt d brute b'.split():             return mode         else:             print('enter either "encrypt" or "e" or "decrypt" or "d" or "brute" or "b".')  def getmessage():     print('enter message:')     return raw_input()  def getkey():     key = 0     while true:         print('enter key number (1-%s)' % (max_key_size))         key = int(raw_input())         if (key >= 1 , key <= max_key_size):             return key  def gettranslatedmessage(mode, message, key):     if mode[0] == 'd':         key = -key     translated = ''      symbol in message:         if symbol.isalpha():             num = ord(symbol)             num += key              if symbol.isupper():                 if num > ord('z'):                     num -= 26                 elif num < ord('a'):                     num += 26             elif symbol.islower():                 if num > ord('z'):                     num -= 26                 elif num < ord('a'):                     num += 26              translated += chr(num)         else:             translated += symbol     return translated  mode = getmode() message = getmessage() if mode[0] != 'b': key = getkey() print('your translated text is:') if mode[0] != 'b': print(gettranslatedmessage(mode, message, key)) else:      key in range(1, max_key_size + 1):          print(key, gettranslatedmessage('decrypt', message, key)) 

how can fix this?

1. do not use += build strings. use ''.join(mylist)
2. do asks: give indented block.