import tkinter


def hello_world():
    print('hello world')


if __name__ == '__main__':
    root = tkinter.Tk()
    frame = tkinter.Frame(root)
    frame.pack()
    button = tkinter.Button(frame, text='Hello World', command=hello_world)
    button.pack(side='top')

    #  run all pending tasks, so that the window is shown up in python 3.6
    root.update_idletasks()

    input('Press enter to exit')  # block the console