You are given a code:

def main_solution(x):
    return (func_13(x, '_') + ('rxgn' + 'gucbk'))

Can you predict the output of `main_solution("ppuqgpobdc")` 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": "ppuqgpobdc"}, "ref_output": "p_p_u_q_g_p_o_b_d_crxgngucbk", "ref_code": "def main_solution(x):\n    return (func_13(x, '_') + ('rxgn' + 'gucbk'))", "funcname": "main_solution"}
rule