I'm trying to make a Caesar cipher encryptor/decryptor in Python, by getting the ASCII index of a letter and adding/subtracting from it. However, it seems to be using Unicode instead because I get letters with accents instead of just English alphabet letters. For example, if I enter the word 'weasel' and encrypt it by 2, what I get is 'yÞĿƲȗʃ'. How do I use ASCII?

Here is my code:

```py
    def manipulate(text, key, e_or_d):
        ciphertext = ''
        for i in text:
            asciiCode = ord(i)
            if e_or_d == 'e':
                key = ord(i) + key
            elif e_or_d == 'd':
                key = ord(i) - key
            newChar = chr(key)
            ciphertext += newChar
        if e_or_d == 'e':
                print('Here is your encrypted text: ')
        elif e_or_d == 'd':
            print('Here is your decrypted text: ')
        print(ciphertext)

    text = input('Enter text: ')
    e_or_d = input('Enter \'e\' for encryption or \'d\' for decryption: ')
    key = int(input('Enter encryption key: '))
    manipulate(text, key, e_or_d)

```

I used `chr` and `ord` here to turn an index into a character and identify the index of a character, respectively.

Sorry if this is incoherent and disorganised.