You are given a code:

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

Can you predict the output of `main_solution("vfenmvt")` 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": "vfenmvt"}, "ref_output": "n\u00abjvg\u00bbe\u00abnfj\u00bbg\u00abeen\u00bbj\u00abgne\u00bbn\u00abjmg\u00bbe\u00abv\u00bb\u00abt\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_1('njge', 4), func_15(x))", "funcname": "main_solution"}
rule