title: Multiple series in a trace for plotly
body: <p>I dynamically generate a pandas dataframe where columns are months, index is day-of-month, and values are cumulative revenue.  This is fairly easy, b/c it just pivots a dataframe that is month/dom/rev.</p>
  
  <p>But now I want to plot it in plotly.  Since every month the columns will expand, I don't want to manually add a trace per month.  But I can't seem to have a single trace incorporate multiple columns.  I could've sworn this was possible.</p>
  
  <pre><code> revs = Scatter(
    x=df.index,
    y=[df['2016-Aug'], df['2016-Sep']],
    name=['rev', 'revvv'],
    mode='lines'
  )
  data=[revs]
  fig = dict( data=data)
  iplot(fig)
  </code></pre>
  
  <p>This generates an empty graph, no errors.  Ideally I'd just pass <code>df[df.columns]</code> to y.  Is this possible?</p>