You are given a code:

def main_solution(x):
    return func_20('qpb', 'xwrjbf')

Can you predict the output of `main_solution("ytqkw")` 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": "ytqkw"}, "ref_output": "qxpwbrjbf", "ref_code": "def main_solution(x):\n    return func_20('qpb', 'xwrjbf')", "funcname": "main_solution"}
rule