You are given a code:

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

Can you predict the output of `main_solution("yoopvmlo")` 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": "yoopvmlo"}, "ref_output": "yoopvmlo1\u00aby\u00bb\u00abx\u00bb\u00abc\u00bb", "ref_code": "def main_solution(x):\n    return (func_23(x, 1) + func_15('yxc'))", "funcname": "main_solution"}
rule