You are given a code:

def main_solution(x):
    return func_13(func_5(x, 'lkkm'), '_')

Can you predict the output of `main_solution("dxd")` 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": "dxd"}, "ref_output": "l_k_k_m_d_x_d", "ref_code": "def main_solution(x):\n    return func_13(func_5(x, 'lkkm'), '_')", "funcname": "main_solution"}
rule