You are given a code:

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

Can you predict the output of `main_solution("lbmopeunfx")` 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": "lbmopeunfx"}, "ref_output": "i\u00abslv\u00bbn\u00abibs\u00bbv\u00abnmi\u00bbs\u00abvon\u00bbi\u00abspv\u00bbn\u00abe\u00bb\u00abu\u00bb\u00abn\u00bb\u00abf\u00bb\u00abx\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_1('isvn', 4), func_15(x))", "funcname": "main_solution"}
rule