You are given a code:

def main_solution(x):
    return func_20('gsv', 'elbk')

Can you predict the output of `main_solution("gnvcbxnujx")` 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": "gnvcbxnujx"}, "ref_output": "geslvbk", "ref_code": "def main_solution(x):\n    return func_20('gsv', 'elbk')", "funcname": "main_solution"}
rule