Helper function to draw the AP score annotation

def _draw_ap_score(self, score, label=None):
        """
        Helper function to draw the AP score annotation
        """
        label = label or "Avg Precision={:0.2f}".format(score)
        if self.ap_score:
            self.ax.axhline(
                y=score, color="r", ls="--", label=label
            )