You are given a code:

def main_solution(x):
    return (func_15('xieya') + func_13('bybvi', '_'))

Can you predict the output of `main_solution("ytxhtklzpp")` 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": "ytxhtklzpp"}, "ref_output": "\u00abx\u00bb\u00abi\u00bb\u00abe\u00bb\u00aby\u00bb\u00aba\u00bbb_y_b_v_i", "ref_code": "def main_solution(x):\n    return (func_15('xieya') + func_13('bybvi', '_'))", "funcname": "main_solution"}
rule