You are given a code:

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

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