You are given a code:

def main_solution(x):
    return func_20((x).upper(), func_15('azvfl'))

Can you predict the output of `main_solution("upecwydxxz")` 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": "upecwydxxz"}, "ref_output": "U\u00abPaE\u00bbC\u00abWzY\u00bbD\u00abXvX\u00bbZ\u00abf\u00bb\u00abl\u00bb", "ref_code": "def main_solution(x):\n    return func_20((x).upper(), func_15('azvfl'))", "funcname": "main_solution"}
rule