You are given a code:

def main_solution(x):
    return func_5(func_13(x, '_'), 'nreu')

Can you predict the output of `main_solution("kzefxwrhjg")` 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": "kzefxwrhjg"}, "ref_output": "nreuk_z_e_f_x_w_r_h_j_g", "ref_code": "def main_solution(x):\n    return func_5(func_13(x, '_'), 'nreu')", "funcname": "main_solution"}
rule