You are given a code:

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

Can you predict the output of `main_solution("umchikn")` 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": "umchikn"}, "ref_output": "\u00abpu_\u00bbw\u00ab_mx\u00bb_\u00abyc\u00bb\u00abh\u00bb\u00abi\u00bb\u00abk\u00bb\u00abn\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), func_13('pwxy', '_'))", "funcname": "main_solution"}
rule