You are given a code:

def main_solution(x):
    return func_20(func_15('cdr'), ('uwzgr' + 'pvbjo'))

Can you predict the output of `main_solution("vls")` 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": "vls"}, "ref_output": "\u00abucw\u00bbz\u00abgdr\u00bbp\u00abvrb\u00bbjo", "ref_code": "def main_solution(x):\n    return func_20(func_15('cdr'), ('uwzgr' + 'pvbjo'))", "funcname": "main_solution"}
rule