You are given a code:

def main_solution(x):
    return (func_13(x, '_') + func_13('ilfb', '-'))

Can you predict the output of `main_solution("axpqtzx")` 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": "axpqtzx"}, "ref_output": "a_x_p_q_t_z_xi-l-f-b", "ref_code": "def main_solution(x):\n    return (func_13(x, '_') + func_13('ilfb', '-'))", "funcname": "main_solution"}
rule