def encrypter(intext, shift, modder):
    plain = list(intext)
    out = ''
    j = 0
    key = list(shift)
    for i in plain:
        if mod > 0:
            x = chr((ord(i) + ord(key[(j % (len(plain) - 1)) % len(key)]) - 48) % 58 + 48)
        if mod < 0:
            x = chr(((ord(i) - ord(key[(j % (len(plain) - 1)) % len(key)]) - 48) % 58 + 48))
        out += x
        j += 1
    return out
sel = raw_input("Encrypt (e)/ Decrypt (d)")
if sel == 'e':
    mod = 1
elif sel == 'd':
    mod = -1
else:
    mod = 0
    print('Enter a proper value!')
if mod != 0:
    print(encrypter(raw_input('Enter the text:'), raw_input('Enter the key-phrase:'), mod)

C:Usersaesha_000pyScriptspython.exe "D:/Programming/Computing GCSE/Resources/functiontest3.py"
Encrypt (e)/ Decrypt (d)e
Enter the text:alex
Enter the key-phrase:pass
]Yd:

Process finished with exit code 0

C:Usersaesha_000pyScriptspython.exe "D:/Programming/Computing GCSE/Resources/functiontest3.py"
Encrypt (e)/ Decrypt (d)d
Enter the text:]Yd:
Enter the key-phrase:pass
a2e>

Process finished with exit code 0