You are given a code:

def main_solution(x):
    return func_20(func_15(x), (x + 'bqknes'))

Can you predict the output of `main_solution("tpwhbv")` 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": "tpwhbv"}, "ref_output": "\u00abttp\u00bbw\u00abhpb\u00bbv\u00abbwq\u00bbk\u00abnhe\u00bbs\u00abb\u00bb\u00abv\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), (x + 'bqknes'))", "funcname": "main_solution"}
rule