You are given a code:

def main_solution(x):
    return ('zye' + 'kheb')

Can you predict the output of `main_solution("prrvnocw")` 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": "prrvnocw"}, "ref_output": "zyekheb", "ref_code": "def main_solution(x):\n    return ('zye' + 'kheb')", "funcname": "main_solution"}
rule