You are given a code:

def main_solution(x):
    return func_20(func_15(x), func_20('vrjrnf', 'yrg'))

Can you predict the output of `main_solution("xzk")` 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": "xzk"}, "ref_output": "\u00abvxy\u00bbr\u00abrzj\u00bbg\u00abrkn\u00bbf", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), func_20('vrjrnf', 'yrg'))", "funcname": "main_solution"}
rule