You are given a code:

def main_solution(x):
    return func_1(func_13('ymayib', '_'), 2)

Can you predict the output of `main_solution("dmtr")` 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": "dmtr"}, "ref_output": "y_m_a_y_i_by_m_a_y_i_b", "ref_code": "def main_solution(x):\n    return func_1(func_13('ymayib', '_'), 2)", "funcname": "main_solution"}
rule