old_contents: from django.core.management.base import NoArgsCommand
  from emissions.models import PageHTML
  from scraper.url_builder import URLBuilder
  from scraper.html_getter import HTMLGetter
  
  
  class Command(NoArgsCommand):
      help = "Download the following 100 emission events."
  
      def handle_noargs(self, **options):
          page = PageHTML.objects.order_by('-tracking_number')[0]
          initial = page.tracking_number
          final = initial + 300
  
          print "Updating from %i to %i" % (initial, final)
  
          url_builder = URLBuilder(initial, final)
          info = HTMLGetter(url_builder)()
  
          print "Success: %i | Failed: %i" % (info['success'], info['failed'])
  
new_contents: from django.core.management.base import NoArgsCommand
  from emissions.models import PageHTML
  from scraper.url_builder import URLBuilder
  from scraper.html_getter import HTMLGetter
  
  
  class Command(NoArgsCommand):
      help = "Download the following 100 emission events."
  
      def handle_noargs(self, **options):
          page = PageHTML.objects.order_by('-tracking_number')[0]
          initial = page.tracking_number
          final = initial + 200
  
          print "Updating from %i to %i" % (initial, final)
  
          url_builder = URLBuilder(initial, final)
          info = HTMLGetter(url_builder)()
  
          print "Success: %i | Failed: %i" % (info['success'], info['failed'])
  
          page = PageHTML.objects.order_by('tracking_number')[0]
          earliest = page.tracking_number
          lookback = earliest - 300
  
          if lookback > 0:
              url_builder = URLBuilder(lookback, earliest)
              info = HTMLGetter(url_builder)()
  
              print "Success: %i | Failed: %i" % (
                  info['success'], info['failed'])
  
subject: Add in look behind