You are given a code:

def main_solution(x):
    return func_20(func_15(x), func_23('aboj', 1))

Can you predict the output of `main_solution("yfbkvyws")` 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": "yfbkvyws"}, "ref_output": "\u00abayb\u00bbo\u00abjf1\u00bb\u00abb\u00bb\u00abk\u00bb\u00abv\u00bb\u00aby\u00bb\u00abw\u00bb\u00abs\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), func_23('aboj', 1))", "funcname": "main_solution"}
rule