def plot_pretty_tick(ax, val, on_x=False, on_y=False):
    if on_x:
        ax.plot([val, val], [0.0, 0.025], 'k-', linewidth=2)
    if on_y:
        ax.plot([(- 0.002), (- 0.0018)], [val, val], 'k-', linewidth=2)
def plot_pretty_tick(ax, val, on_x=False, on_y=False):
    if on_x:
        ax.plot([val, val], [0.0, 0.025], 'k-', linewidth=2)
    if on_y:
        ax.plot([(- 0.002), (- 0.0018)], [val, val], 'k-', linewidth=2)