You are given a code:

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

Can you predict the output of `main_solution("cszkcyfgn")` 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": "cszkcyfgn"}, "ref_output": "c_s_z_k_c_y_f_g_n_x_c_g_x_r", "ref_code": "def main_solution(x):\n    return func_13((x + 'xcgxr'), '_')", "funcname": "main_solution"}
rule