# Learn String Manipulation by Building a Cipher - Step 75

### Tell us what’s happening:

i did what the instructions told me to do, add .isalpha() to char, but i keep getting errors. what am i doing wrong?
(i know there was a similar previous post saying an indentation error is what occurred, but i cannot figure out if/where that’s occurring)

``````text = 'Hello Zaira!'
custom_key = 'python'

def vigenere(message, key, direction=1):
key_index = 0
alphabet = 'abcdefghijklmnopqrstuvwxyz'
final_message = ''

for char in message.lower():

/* User Editable Region */

# Append space to the message
if char.isalpha() == ' ':
final_message += char

/* User Editable Region */

else:
# Find the right key character to encode/decode
key_char = key[key_index % len(key)]
key_index += 1

# Define the offset and the encrypted/decrypted letter
offset = alphabet.index(key_char)
index = alphabet.find(char)
new_index = (index + offset*direction) % len(alphabet)
final_message += alphabet[new_index]

return final_message

encryption = vigenere(text, custom_key)
print(encryption)
decryption = vigenere(encryption, custom_key, -1)
print(decryption)

``````

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36`

### Challenge Information:

Learn String Manipulation by Building a Cipher - Step 75

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Hello Yuh,

islapha() returns `True` or `False` depending on if `char` is a letter or not. So essentially you are now comparing that `True` or `False` against an empty space.

All you need to know is if `char` is a letter, if it is, you add it to the `final_message` variable.

2 Likes

Thank you, I have been experiencing the same difficulty!!

1 Like

thank you so much, i got it now!

1 Like

Hasn’t worked for me