title: Plotting sets from Pandas df and Type Error unhashable type: 'set'
body: <p>I have a dataframe with a column of sets:</p>
  <pre><code>df = pd.DataFrame([['Alex',{33, 34}],['Bob',{33}],['Clarke',{33, 34}]], columns = ['names', 'indicators']).
  </code></pre>
  <p>I would like to plot the frequency of values in df['indicators'] to get a sense of what combinations of indicators take place. I.e., here I'd like a plot that shows {33, 34} shows up twice and {33} shows up once. Letting seaborn be sb, I'd normally make a histogram:</p>
  <pre><code>sb.countplot(data = df, x = 'indicators')
  </code></pre>
  <p>But I get TypeError: unhashable type: 'set' when I try this. I've tried converting the arguments from sets to lists or np.array() to no avail.</p>