You are given a code:

def main_solution(x):
    return func_20(func_15('kac'), ('oei' + 'hnrkp'))

Can you predict the output of `main_solution("bbnf")` 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": "bbnf"}, "ref_output": "\u00aboke\u00bbi\u00abhan\u00bbr\u00abkcp\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15('kac'), ('oei' + 'hnrkp'))", "funcname": "main_solution"}
rule