You are given a code:

def main_solution(x):
    return func_20(func_15('vqw'), func_13('mssww', '_'))

Can you predict the output of `main_solution("tuudb")` 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": "tuudb"}, "ref_output": "\u00abmv_\u00bbs\u00ab_qs\u00bb_\u00abww_\u00bbw", "ref_code": "def main_solution(x):\n    return func_20(func_15('vqw'), func_13('mssww', '_'))", "funcname": "main_solution"}
rule