You are given a code:

def main_solution(x):
    return (func_13('mhrf', '_') + func_15('plmpsr'))

Can you predict the output of `main_solution("hezryfnpw")` 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": "hezryfnpw"}, "ref_output": "m_h_r_f\u00abp\u00bb\u00abl\u00bb\u00abm\u00bb\u00abp\u00bb\u00abs\u00bb\u00abr\u00bb", "ref_code": "def main_solution(x):\n    return (func_13('mhrf', '_') + func_15('plmpsr'))", "funcname": "main_solution"}
rule