def METHOD_NAME(self, *args):
    if self.fill:
        with self.loops.hold_sync():
            self.loops.fill = "inside"
            self.loops.fill_opacities = [0.2] * len(self.loops.y)
    else:
        self.loops.fill = "none"
        self.loops.fill_opacities = [0.0] * len(self.loops.y)