You are given a code:

def main_solution(x):
    return (func_13(x, '_') + ('xmmzj' + 'qiseqp'))

Can you predict the output of `main_solution("kadqurfvuv")` 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": "kadqurfvuv"}, "ref_output": "k_a_d_q_u_r_f_v_u_vxmmzjqiseqp", "ref_code": "def main_solution(x):\n    return (func_13(x, '_') + ('xmmzj' + 'qiseqp'))", "funcname": "main_solution"}
rule