You are given a code:

def main_solution(x):
    return (func_15(x) + func_9('bff'))

Can you predict the output of `main_solution("tnaavcsg")` 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": "tnaavcsg"}, "ref_output": "\u00abt\u00bb\u00abn\u00bb\u00aba\u00bb\u00aba\u00bb\u00abv\u00bb\u00abc\u00bb\u00abs\u00bb\u00abg\u00bbbffffb", "ref_code": "def main_solution(x):\n    return (func_15(x) + func_9('bff'))", "funcname": "main_solution"}
rule