You are given a code:

def main_solution(x):
    return func_20('wtuvb', 'ytnn')

Can you predict the output of `main_solution("pmlywkqbvb")` 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": "pmlywkqbvb"}, "ref_output": "wyttunvnb", "ref_code": "def main_solution(x):\n    return func_20('wtuvb', 'ytnn')", "funcname": "main_solution"}
rule