title: Plot dictionary of dictionaries in one barplot
body: <p>I've got a dictionary that looks like this </p>
  
  <pre><code>d = {
      'a' : {'L1':2, 'L2':5, 'L3':8},
      'b' : {'L1':4, 'L2':7, 'L3':10},
      'c' : {'L1':19, 'L2':0, 'L3':1},
  }
  </code></pre>
  
  <p>I would like to have a plot where the x axis contains my keys and each key has 3 barplots that correspond to the values of L1, L2 and L3.<br>
  All in all, my plot would contain 9 bars grouped by the key (so 3 groups of 3 bars).</p>
  
  <p>So far, what I could do was convert my dictionary to a dataframe and then use seaborn's barplot for each of the keys but that leaves my with 3 different plots.</p>
  
  <p>Is it possible to have one plot with all the informations ?</p>
  
  <p>Many thanks.</p>