You are given a code:

def main_solution(x):
    return func_20(func_15(x), func_20('gopo', 'tdv'))

Can you predict the output of `main_solution("tdap")` 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": "tdap"}, "ref_output": "\u00abgtt\u00bbo\u00abddp\u00bbv\u00aboa\u00bb\u00abp\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), func_20('gopo', 'tdv'))", "funcname": "main_solution"}
rule