You are given a code:

def main_solution(x):
    return func_20(func_3('lfty'), func_13('yszhus', '_'))

Can you predict the output of `main_solution("vju")` 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": "vju"}, "ref_output": "fyl_tsy_z_h_u_s", "ref_code": "def main_solution(x):\n    return func_20(func_3('lfty'), func_13('yszhus', '_'))", "funcname": "main_solution"}
rule