title: Plotly: Add line to bar chart
body: <p>I have a plotly bar chart, from a dataframe:</p>
  
  <pre><code>fig = df.iplot(asFigure=True, kind='bar', barmode = 'relative')
  py.iplot(fig)
  </code></pre>
  
  <p>Is it possible to turn one of the columns in the data frame into a line series?</p>