You are given a code:

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

Can you predict the output of `main_solution("ydrb")` 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": "ydrb"}, "ref_output": "\u00abm\u00bb\u00abp\u00bb\u00abj\u00bb\u00abp\u00bb\u00abm\u00bb\u00abp\u00bb\u00abj\u00bb\u00abp\u00bb\u00abm\u00bb\u00abp\u00bb\u00abj\u00bb\u00abp\u00bb\u00abm\u00bb\u00abp\u00bb\u00abj\u00bb\u00abp\u00bb", "ref_code": "def main_solution(x):\n    return func_15(func_1('mpjp', 4))", "funcname": "main_solution"}
rule