You are given a code:

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

Can you predict the output of `main_solution("xmyv")` 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": "xmyv"}, "ref_output": "\u00ab_r_\u00bb_\u00ab_m_\u00bb_\u00ab_c_\u00bb_\u00ab_y_\u00bb_\u00ab_d_\u00bb_\u00ab_n_\u00bb", "ref_code": "def main_solution(x):\n    return func_13(func_15('rmcydn'), '_')", "funcname": "main_solution"}
rule