You are given a code:

def main_solution(x):
    return ('qfkggu' + 'ymkv')

Can you predict the output of `main_solution("ninztwht")` 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": "ninztwht"}, "ref_output": "qfkgguymkv", "ref_code": "def main_solution(x):\n    return ('qfkggu' + 'ymkv')", "funcname": "main_solution"}
rule