You are given a code:

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

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