You are given a code:

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

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