You are given a code:

def main_solution(x):
    return func_20(func_15(x), func_13('rxfchm', '_'))

Can you predict the output of `main_solution("phsvk")` 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": "phsvk"}, "ref_output": "\u00abrp_\u00bbx\u00ab_hf\u00bb_\u00abcs_\u00bbh\u00ab_vm\u00bb\u00abk\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), func_13('rxfchm', '_'))", "funcname": "main_solution"}
rule