You are given a code:

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

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