title: Stacked bar charts where each column is a bar chart with multiple columns in Altair
body: <p>I'd like to draw similar chart that was requested in
  <a href="https://stackoverflow.com/questions/47801705/stacked-bar-chart-across-multiple-columns">Stacked bar chart across multiple columns</a>
  but it's with R, I want to use Python, hopefully with Atair.</p>