code: def formatfooter(self, previous_month, next_month):
          
          footer = '<tfoot><tr>' \
                   '<td colspan="3" class="prev">%s</td>' \
                   '<td class="pad">&nbsp;</td>' \
                   '<td colspan="3" class="next">%s</td>' \
                   '</tr></tfoot>'
          if previous_month:
              previous_content = '<a href="%s" class="previous-month">%s</a>' % (
                  reverse('zinnia:entry_archive_month', args=[
                      previous_month.strftime('%Y'),
                      previous_month.strftime('%m')]),
                  date_format(previous_month, 'YEAR_MONTH_FORMAT'))
          else:
              previous_content = '&nbsp;'
  
          if next_month:
              next_content = '<a href="%s" class="next-month">%s</a>' % (
                  reverse('zinnia:entry_archive_month', args=[
                      next_month.strftime('%Y'),
                      next_month.strftime('%m')]),
                  date_format(next_month, 'YEAR_MONTH_FORMAT'))
          else:
              next_content = '&nbsp;'
  
          return footer % (previous_content, next_content)
docs: Return a footer for a previous and next month.