You are given a code:

def main_solution(x):
    return (('ydr' + x) + func_13(x, '|'))

Can you predict the output of `main_solution("fkfkeu")` 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": "fkfkeu"}, "ref_output": "ydrfkfkeuf|k|f|k|e|u", "ref_code": "def main_solution(x):\n    return (('ydr' + x) + func_13(x, '|'))", "funcname": "main_solution"}
rule