You are given a code:

def main_solution(x):
    return (func_15('fpve') + func_23('jaf', 1))

Can you predict the output of `main_solution("pre")` 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": "pre"}, "ref_output": "\u00abf\u00bb\u00abp\u00bb\u00abv\u00bb\u00abe\u00bbjaf1", "ref_code": "def main_solution(x):\n    return (func_15('fpve') + func_23('jaf', 1))", "funcname": "main_solution"}
rule