[Matplotlib-users] accessing axis artist objects for an axes object

Python: 3.5
Matplotlib: 1.5.2

I'm trying to invert the tick labels on a Cartopy map, and I found
this Matplotlib example:

ax.axis[:].invert_ticklabel_direction()

found here:
http://matplotlib.org/mpl_toolkits/axes_grid/users/axisartist.html

My problem is that any Axes object (or child class thereof) that I've
experimented with says that the axis attribute is a *method*, not a
sequence as I infer from the above example.

How do I get the axisartists for a bog-standard Axes instance?

Thanks in advance,

Mike