You are given a code:

def main_solution(x):
    return (func_13('smdhyi', '_') + func_15('whlpfw'))

Can you predict the output of `main_solution("ggfcdq")` 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": "ggfcdq"}, "ref_output": "s_m_d_h_y_i\u00abw\u00bb\u00abh\u00bb\u00abl\u00bb\u00abp\u00bb\u00abf\u00bb\u00abw\u00bb", "ref_code": "def main_solution(x):\n    return (func_13('smdhyi', '_') + func_15('whlpfw'))", "funcname": "main_solution"}
rule