You are given a code:

def main_solution(x):
    return func_20(func_15('wwiimz'), func_13('rtl', '_'))

Can you predict the output of `main_solution("njsvfr")` 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": "njsvfr"}, "ref_output": "\u00abrw_\u00bbt\u00ab_wl\u00bb\u00abi\u00bb\u00abi\u00bb\u00abm\u00bb\u00abz\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_15('wwiimz'), func_13('rtl', '_'))", "funcname": "main_solution"}
rule