You are given a code:

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

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