You are given a code:

def main_solution(x):
    return func_20(func_5('qvnojo', 'no'), func_13(x, '_'))

Can you predict the output of `main_solution("cfbuuiwtmf")` 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": "cfbuuiwtmf"}, "ref_output": "nco_qfv_nbo_juo_u_i_w_t_m_f", "ref_code": "def main_solution(x):\n    return func_20(func_5('qvnojo', 'no'), func_13(x, '_'))", "funcname": "main_solution"}
rule