You are given a code:

def main_solution(x):
    return func_5(func_4('tts'), 'wux')

Can you predict the output of `main_solution("gvb")` 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": "gvb"}, "ref_output": "wuxtts", "ref_code": "def main_solution(x):\n    return func_5(func_4('tts'), 'wux')", "funcname": "main_solution"}
rule