You are given a code:

def main_solution(x):
    return (func_15('lnkbzm')).upper()

Can you predict the output of `main_solution("ffg")` 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": "ffg"}, "ref_output": "\u00abL\u00bb\u00abN\u00bb\u00abK\u00bb\u00abB\u00bb\u00abZ\u00bb\u00abM\u00bb", "ref_code": "def main_solution(x):\n    return (func_15('lnkbzm')).upper()", "funcname": "main_solution"}
rule