You are given a code:

def main_solution(x):
    return func_20(func_20(x, 'uumqx'), func_15('wbu'))

Can you predict the output of `main_solution("ljthuxk")` 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": "ljthuxk"}, "ref_output": "l\u00abuwj\u00bbu\u00abtbm\u00bbh\u00abquu\u00bbxxk", "ref_code": "def main_solution(x):\n    return func_20(func_20(x, 'uumqx'), func_15('wbu'))", "funcname": "main_solution"}
rule