You are given a code:

def main_solution(x):
    return func_20(func_20('rkkrhv', 'tuanyk'), func_15('fir'))

Can you predict the output of `main_solution("tfr")` without writing any code? Please reason and put your final answer in the following json format: {"output": <your output>}, where <your output> should be the final string.
user
{"ref_input": {"x": "tfr"}, "ref_output": "r\u00abtfk\u00bbu\u00abkia\u00bbr\u00abnrh\u00bbyvk", "ref_code": "def main_solution(x):\n    return func_20(func_20('rkkrhv', 'tuanyk'), func_15('fir'))", "funcname": "main_solution"}
rule