You are given a code:

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

Can you predict the output of `main_solution("ecmc")` 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": "ecmc"}, "ref_output": "l\u00ab_eu\u00bb_\u00abjc\u00bb\u00abm\u00bb\u00abc\u00bb", "ref_code": "def main_solution(x):\n    return func_20(func_13('luj', '_'), func_15(x))", "funcname": "main_solution"}
rule