You are given a code:

def main_solution(x):
    return func_20(func_13('vqxw', '_'), func_15('rnmkyf'))

Can you predict the output of `main_solution("iopuaepyg")` 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": "iopuaepyg"}, "ref_output": "v\u00ab_rq\u00bb_\u00abxn_\u00bbw\u00abm\u00bb\u00abk\u00bb\u00aby\u00bb\u00abf\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_13('vqxw', '_'), func_15('rnmkyf'))", "funcname": "main_solution"}
rule