import tkinter as tk

def donothing():
    x=0

window=tk.Tk()

menubar=tk.Menu(window)
filemenu=tk.Menu(menubar,tearoff=0)
"""filemenu.add_command(label='New',command=donothing)
filemenu.add_command(label='Open',command=donothing)
filemenu.add_command(label='Save',command=donothing)
filemenu.add_separator()"""
menubar.add_command(label='exit',command=window.quit)
menubar.add_cascade(label='file',menu=filemenu)

window.config(menu=menubar)
window.mainloop()