You are given a code:

def main_solution(x):
    return func_20('kvr', 'fondy')

Can you predict the output of `main_solution("tbvogtst")` 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": "tbvogtst"}, "ref_output": "kfvorndy", "ref_code": "def main_solution(x):\n    return func_20('kvr', 'fondy')", "funcname": "main_solution"}
rule