You are given a code:

def main_solution(x):
    return func_20('eay', 'sof')

Can you predict the output of `main_solution("ubxbyn")` 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": "ubxbyn"}, "ref_output": "esaoyf", "ref_code": "def main_solution(x):\n    return func_20('eay', 'sof')", "funcname": "main_solution"}
rule