You are given a code:

def main_solution(x):
    return ('tmj' + 'fnfy')

Can you predict the output of `main_solution("nqkxbxcvn")` 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": "nqkxbxcvn"}, "ref_output": "tmjfnfy", "ref_code": "def main_solution(x):\n    return ('tmj' + 'fnfy')", "funcname": "main_solution"}
rule