You are given a code:

def main_solution(x):
    return func_20(('zzxh' + x), func_15('kdrtt'))

Can you predict the output of `main_solution("nffkar")` 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": "nffkar"}, "ref_output": "z\u00abzkx\u00bbh\u00abndf\u00bbf\u00abkra\u00bbr\u00abt\u00bb\u00abt\u00bb", "ref_code": "def main_solution(x):\n    return func_20(('zzxh' + x), func_15('kdrtt'))", "funcname": "main_solution"}
rule