You are given a code:

def main_solution(x):
    return func_3(func_5('tbyi', 'opkw'))

Can you predict the output of `main_solution("rbt")` 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": "rbt"}, "ref_output": "bikoptwy", "ref_code": "def main_solution(x):\n    return func_3(func_5('tbyi', 'opkw'))", "funcname": "main_solution"}
rule