title: How can I customize the legend with Seaborn 0.12 objects?
body: <p>The new Seaborn objects (v 0.12) are great but I struggle to deal with legend customization. Especially when using matplotlib to define subplots. My code:</p>
  <pre><code>f, ((ax1, ax2), (ax3, ax4)) = plt.subplots(2, 2, figsize=(3.5, 3.5), gridspec_kw={'width_ratios':[1.5,1]}, dpi=dpi)
  (
       so.Plot(sert_neurons, x='mod_index_late', y='opto_mod_roc', color='sig_modulation')
       .add(so.Dot(pointsize=2))
       .add(so.Line(color='k'), so.PolyFit(order=1), color=None)
       .limit(x=[-1, 1], y=[-1, 1])
       .label(x='Spontaneous 5-HT modulation', y='Task evoked 5-TH modulation')
       .on(ax1)
       .plot()
  )
  plt.tight_layout()
  sns.despine(trim=True)
  </code></pre>
  <p>Produces <a href="https://i.stack.imgur.com/bhtpk.png" rel="nofollow noreferrer">this figure</a> which does not have any legend (it seems to be located outside of the plot limits). When I do something like
  <code>ax1.legend(frameon=False, prop={'size': 5}, loc='upper left')</code> I get the message <code>No artists with labels found to put in legend.</code> How can I move the legend to within the subplot and customize it's appearance?</p>