You are given a code:

def main_solution(x):
    return func_13(func_20(x, 'cqvwnq'), '_')

Can you predict the output of `main_solution("eptxlfvzhq")` 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": "eptxlfvzhq"}, "ref_output": "e_c_p_q_t_v_x_w_l_n_f_q_v_z_h_q", "ref_code": "def main_solution(x):\n    return func_13(func_20(x, 'cqvwnq'), '_')", "funcname": "main_solution"}
rule