You are given a code:

def main_solution(x):
    return func_20((x).lower(), func_15('qpfw'))

Can you predict the output of `main_solution("brwvyu")` 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": "brwvyu"}, "ref_output": "b\u00abrqw\u00bbv\u00abypu\u00bb\u00abf\u00bb\u00abw\u00bb", "ref_code": "def main_solution(x):\n    return func_20((x).lower(), func_15('qpfw'))", "funcname": "main_solution"}
rule