You are given a code:

def main_solution(x):
    return func_20(func_15(x), func_1('uutbxw', 4))

Can you predict the output of `main_solution("vaspgooz")` 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": "vaspgooz"}, "ref_output": "\u00abuvu\u00bbt\u00abbax\u00bbw\u00abusu\u00bbt\u00abbpx\u00bbw\u00abugu\u00bbt\u00abbox\u00bbw\u00abuou\u00bbt\u00abbzx\u00bbw", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), func_1('uutbxw', 4))", "funcname": "main_solution"}
rule