You are given a code:

def main_solution(x):
    return (func_3('qhey') + func_13('ycibpl', '_'))

Can you predict the output of `main_solution("vkh")` 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": "vkh"}, "ref_output": "ehqyy_c_i_b_p_l", "ref_code": "def main_solution(x):\n    return (func_3('qhey') + func_13('ycibpl', '_'))", "funcname": "main_solution"}
rule