You are given a code:

def main_solution(x):
    return (func_13(x, '_') + func_15('ldy'))

Can you predict the output of `main_solution("esinlunktc")` 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": "esinlunktc"}, "ref_output": "e_s_i_n_l_u_n_k_t_c\u00abl\u00bb\u00abd\u00bb\u00aby\u00bb", "ref_code": "def main_solution(x):\n    return (func_13(x, '_') + func_15('ldy'))", "funcname": "main_solution"}
rule