You are given a code:

def main_solution(x):
    return func_4('yabjil')

Can you predict the output of `main_solution("udci")` 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": "udci"}, "ref_output": "yabjil", "ref_code": "def main_solution(x):\n    return func_4('yabjil')", "funcname": "main_solution"}
rule