title: Folding multiple rows with openpyxl
body: <p>Is there a way to fold multiple rows using <code>openpyxl</code>? There doesn't appear to be a row equivalent to the example found on the <a href="http://openpyxl.readthedocs.org/en/latest/usage.html" rel="noreferrer">openpyxl simple usage page</a>.</p>
  
  <pre><code>import openpyxl
  wb = openpyxl.Workbook(True)
  ws = wb.create_sheet()
  ws.column_dimensions.group('A','D', hidden=True)
  wb.save('group.xlsx')
  </code></pre>