You are given a code:

def main_solution(x):
    return func_20(func_4('hgrbuu'), func_15('ketk'))

Can you predict the output of `main_solution("ragjvtfi")` 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": "ragjvtfi"}, "ref_output": "h\u00abgkr\u00bbb\u00abueu\u00bb\u00abt\u00bb\u00abk\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_4('hgrbuu'), func_15('ketk'))", "funcname": "main_solution"}
rule