You are given a code:

def main_solution(x):
    return func_5(func_13(x, '_'), 'ogp')

Can you predict the output of `main_solution("gtrjurbtyx")` 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": "gtrjurbtyx"}, "ref_output": "ogpg_t_r_j_u_r_b_t_y_x", "ref_code": "def main_solution(x):\n    return func_5(func_13(x, '_'), 'ogp')", "funcname": "main_solution"}
rule