Get highest zorder object from matplotlib figure

Question

Given a matplotlib figure or plot, how can I retrieve the value of the highest zorder object? For instance, retrieving the value of 5 in this example:

import matplotlib.pyplot as plt
import numpy as np
fig, ax = plt.subplots(1)
ax.plot(np.arange(10), np.arange(10), zorder=5, linewidth=5)
ax.plot(np.arange(10), np.arange(10)[::-1], zorder=1, linewidth=5)
# implement: get_maximum_zorder(ax) 

Answer 1

This can be done by accessing the axes's children, each of which has a zorder attribute.

max([_.zorder for _ in ax.get_children()])