You are given a code:

def main_solution(x):
    return func_5(func_19('mhwuo', 1), 'ktok')

Can you predict the output of `main_solution("vlaaotpgb")` 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": "vlaaotpgb"}, "ref_output": "ktokhwuom", "ref_code": "def main_solution(x):\n    return func_5(func_19('mhwuo', 1), 'ktok')", "funcname": "main_solution"}
rule