human
Complete this python program:
def demo():
assistant
#Here is the Python program you requested.

    """A simple demonstration showing how to use canvas widgets.
    """
    def fill(cw):
        from random import randint
        cw['fill'] = ('#00%04d' % randint(0, 9999))
    def color(cw):
        from random import randint
        cw['color'] = ('#ff%04d' % randint(0, 9999))
    cf = CanvasFrame(closeenough=10, width=300, height=300)
    c = cf.canvas()
    ct3 = TextWidget(c, 'hiya    there', draggable=1)
    ct2 = TextWidget(c, 'o        o\n||\n___\n        U', draggable=1, justify='center')
    co = OvalWidget(c, ct2, outline='red')
    ct = TextWidget(c, 'o        o\n||\n\\___/', draggable=1, justify='center')
    cp = ParenWidget(c, ct, color='red')
    cb = BoxWidget(c, cp, fill='cyan', draggable=1, width=3, margin=10)
    equation = SequenceWidget(c, SymbolWidget(c, 'forall'), TextWidget(c, 'x'), SymbolWidget(c, 'exists'), TextWidget(c, 'y:    '), TextWidget(c, 'x'), SymbolWidget(c, 'notequal'), TextWidget(c, 'y'))
    space = SpaceWidget(c, 0, 30)
    cstack = StackWidget(c, cb, ct3, space, co, equation, align='center')
    foo = TextWidget(c, 'try    clicking\nand    dragging', draggable=1, justify='center')
    cs = SequenceWidget(c, cstack, foo)
    zz = BracketWidget(c, cs, color='green4', width=3)
    cf.add_widget(zz, 60, 30)
    cb.bind_click(fill)
    ct.bind_click(color)
    co.bind_click(fill)
    ct2.bind_click(color)
    ct3.bind_click(color)
    cf.mainloop()