How can I save and close AutoCAD application with python?

Question

I'm trying to save and close an AutoCAD application. I've tried to use .Quit() but didn't work.

from comtypes import COMError
from comtypes.client import CreateObject, GetActiveObject


def main():
    # Capture opened AutoCAD
    try:
        acad = GetActiveObject("AutoCAD.Application")

    # Open new AutoCAD instance
    except (OSError, COMError):
        acad = CreateObject("AutoCAD.Application", dynamic=True)

    # Path to dwg file
    filepath = r"C:\test.dwg"  # Replace it with the actual drawing path
    doc = acad.Documents.Open(filepath)

    load_lisp = '(load "C:/DemoExtracao.fas") '  # Notice that the last SPACE is equivalent to

    doc.SendCommand(load_lisp)

    execute_lisp = "(DEMO) "

    doc.SendCommand(execute_lisp)
    
    doc.Quit() # This line doesn't work


# Início da aplicação principal
if __name__ == "__main__":
    main()

How can I save and close my AutoCAD application?