You are given a code:

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

Can you predict the output of `main_solution("mqcyymdj")` 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": "mqcyymdj"}, "ref_output": "tnxe_r_v_e_z", "ref_code": "def main_solution(x):\n    return func_5(func_13('ervez', '_'), 'tnx')", "funcname": "main_solution"}
rule