You are given a code:

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

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