You are given a code:

def main_solution(x):
    return func_20(func_20(x, x), func_15('fefcpw'))

Can you predict the output of `main_solution("nzljxxiyu")` 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": "nzljxxiyu"}, "ref_output": "n\u00abnfz\u00bbz\u00ablel\u00bbj\u00abjfx\u00bbx\u00abxcx\u00bbi\u00abipy\u00bby\u00abuwu\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_20(x, x), func_15('fefcpw'))", "funcname": "main_solution"}
rule