cipher.py

alphabet = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

def caesar(start_text, shift_amount,cipher_direction):
    end_text = ""
    cipher_direction = cipher_direction.lower()
    if cipher_direction == "decode":
        shift_amount *= -1
    for char in start_text:
        if char in alphabet:
            position = alphabet.index(char)
            new_position = position + shift_amount
            if new_position > 51:
                new_position -= 51
            end_text += alphabet[new_position]
        else:
            end_text += char
    return end_text