def METHOD_NAME(self):
    # X-axis.
    plt.plot(self.XLIM, np.zeros_like(self.XLIM), 'k')
    # Tick mark centered at the origin.
    tick_pos = -0.5 * np.asarray(self.TICK_DIMS)
    self.ax.add_patch(plt.Rectangle(tick_pos, *self.TICK_DIMS, fc='k'))