You are given a code:

def main_solution(x):
    return func_5(('slqt' + 'vefab'), 'mhdx')

Can you predict the output of `main_solution("nbu")` 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": "nbu"}, "ref_output": "mhdxslqtvefab", "ref_code": "def main_solution(x):\n    return func_5(('slqt' + 'vefab'), 'mhdx')", "funcname": "main_solution"}
rule