You are given a code:

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

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