You are given a code:

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

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