decoder.py

import sys

simple_table = {
    ":encoded1:" : "a",
    ":encoded2:" : "b",
    ":encoded3:" : "c",
    ":encoded4:" : "d",
    ":encoded5:" : "e",
    ":encoded6:" : "f",
    ":encoded7:" : "g",
    ":encoded8:" : "h",
    ":encoded9:" : "i",
    ":encoded10:" : "j",
    ":encodedb1:" : "k",
    ":encodedb2:" : "l",
    ":encodedb3:" : "m",
    ":encodedb4:" : "n",
    ":encodedb5:" : "o",
    ":encodedb6:" : "p",
    ":encodedb7:" : "q",
    ":encodedb8:" : "r",
    ":encodedb9:" : "s",
    ":encodedb10:" : "t",
    ":encodedc1:" : "u",
    ":encodedc2:" : "v",
    ":encodedc3:" : "w",
    ":encodedc4:" : "x",
    ":encodedc5:" : "y",
    ":encodedc6:" : "z"
}

def decode_message(str):
    decoded = ""
    codes = str.split(" ")

    for code in codes:
        decoded += simple_table[code.strip()]

    return decoded

message = sys.argv[1:][0].lower()
encoded = decode_message(message)
print(encoded)