You are given a code:

def main_solution(x):
    return func_20(func_11(x, 4), func_15('rdfhk'))

Can you predict the output of `main_solution("romoiyhf")` 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": "romoiyhf"}, "ref_output": "v\u00absrq\u00bbs\u00abmdc\u00bbl\u00abjf\u00bb\u00abh\u00bb\u00abk\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_11(x, 4), func_15('rdfhk'))", "funcname": "main_solution"}
rule