una funcion que genere un cufrado cesar

def cesar(text, key):
    alphabet = "abcdefghijklmnopqrstuvwxyz"
    new_text = ""
    for i in text:
        if i in alphabet:
            position = alphabet.index(i)
            new_position = (position + key) % 26
            new_character = alphabet[new_position]
            new_text += new_character
        else:
            new_text += i
    return new_text