You are given a code:

def main_solution(x):
    return (func_5(x, 'gcut') + func_13('kplw', '_'))

Can you predict the output of `main_solution("ynvxzb")` 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": "ynvxzb"}, "ref_output": "gcutynvxzbk_p_l_w", "ref_code": "def main_solution(x):\n    return (func_5(x, 'gcut') + func_13('kplw', '_'))", "funcname": "main_solution"}
rule