You are given a code:

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

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