You are given a code:

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

Can you predict the output of `main_solution("utlfddgwoc")` 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": "utlfddgwoc"}, "ref_output": "a_x_x_h_g_u_t_l_f_d_d_g_w_o_c", "ref_code": "def main_solution(x):\n    return func_13(('axxhg' + x), '_')", "funcname": "main_solution"}
rule