import codecs
def rot13(text: str) -> str:
"""
Apply the ROT13 cipher to a string.
ROT13 rotates each letter by 13 positions in the alphabet.
Non-alphabetic characters are left unchanged.
Applying ROT13 twice returns the original text.
Args:
text: The text to encode or decode.
Returns:
The ROT13-transformed string.
"""
return codecs.encode(text, "rot_13")
def main() -> None:
input_text = "Hello, World! 123"
encoded = rot13(input_text)
decoded = rot13(encoded)
print(f"Input : {input_text}")
print(f"Encoded : {encoded}")
print(f"Decoded : {decoded}")
if __name__ == "__main__":
main()
'''
run:
Input : Hello, World! 123
Encoded : Uryyb, Jbeyq! 123
Decoded : Hello, World! 123
'''
