1EMPTY_STRING = ''
 2
 3
 4def plugboard(base_text, pairs):
 5    return EMPTY_STRING.join([new_mapping(symbol, pairs) for symbol in base_text])
 6
 7
 8def rotor(base_text, alphabet_map):
 9    return EMPTY_STRING.join([alphabet_map.get(symbol, symbol) for symbol in base_text])
10
11
12def enigma_encrypt(plugboard_position, rotor_position):
13    def decorator(function):
14        def engine_encrypt(text):
15            return function(rotor(plugboard(text, plugboard_position), rotor_position))
16        return engine_encrypt
17    return decorator
18
19
20def enigma_decrypt(plugboard_position, rotor_position):
21    def decorator(function):
22        def engine_decrypt(text):
23            return function(plugboard(reverse_rotor(text, rotor_position), plugboard_position))
24        return engine_decrypt
25    return decorator
26
27
28def new_mapping(symbol, pairs):
29    return next((counterpart(symbol, pair) for pair in pairs if symbol in pair), symbol)
30
31
32def counterpart(symbol, pair):
33    return (pair - {symbol}).pop()
34
35
36def reverse_rotor(text, pairs):
37    return rotor(text, reverse_dictionary(pairs))
38
39
40def reverse_dictionary(dictionary):
41    return {value: key for key, value in dictionary.items()}