You are given a code:

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

Can you predict the output of `main_solution("xxqy")` 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": "xxqy"}, "ref_output": "v_y_v_l_j_y_i_o_d_m_v", "ref_code": "def main_solution(x):\n    return func_13(('vyvlj' + 'yiodmv'), '_')", "funcname": "main_solution"}
rule