You are given a code:

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

Can you predict the output of `main_solution("vrkszff")` 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": "vrkszff"}, "ref_output": "\u00abvor\u00bbk\u00abstz\u00bbf\u00abfiv\u00bbrkszff", "ref_code": "def main_solution(x):\n    return func_20(func_15('oti'), (x + x))", "funcname": "main_solution"}
rule