You are given a code:

def main_solution(x):
    return (func_13('iomnv', '_') + (x + 'uxf'))

Can you predict the output of `main_solution("lqxtllv")` 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": "lqxtllv"}, "ref_output": "i_o_m_n_vlqxtllvuxf", "ref_code": "def main_solution(x):\n    return (func_13('iomnv', '_') + (x + 'uxf'))", "funcname": "main_solution"}
rule