def build(self):
dot = Widget()
with dot.canvas:
self.color = Color(0.5, 0.5, 1)
Ellipse(pos=(100, 100), size=(100, 100))
anim = anims.cycle(v=(0.2, 0.8), duration=0.1, anim_end=dict(v=self.color.v))
anim.start(self.color)
anims.Clock.schedule_once(lambda *_: anim.stop(self.color), 3)
return dot