Xlabel and ylabel are not shown

[David Lowry-Duda]

There are two main ways of creating a plot in matplotlib: the pyplot 
MATLAB-style system and an object-oriented system. Although many 
tutorials online use the MATLAB interface, it is usually a good idea to 
use the object-oriented system.

I mention this here because after one calls `plt.plot(<stuff>)`, it can 
be a bit nonintuitive how to alter the plot through the MATLAB-style 
interface. I think this might be happening here.

If you provide a complete minimally-running-code sample, I'd be happy to 
go through it in a bit more detail.

- David Lowry-Duda