You are given a code:

def main_solution(x):
    return func_20(func_15(x), func_20('istrbt', x))

Can you predict the output of `main_solution("hhjoc")` 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": "hhjoc"}, "ref_output": "\u00abihh\u00bbs\u00abhht\u00bbj\u00abrjo\u00bbb\u00abcot\u00bb\u00abc\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15(x), func_20('istrbt', x))", "funcname": "main_solution"}
rule