old_contents: from django.http import HttpResponse
  from django.shortcuts import get_object_or_404
  from django.utils.translation import gettext as _
  
  from osmaxx.excerptexport.models import extraction_order, ExtractionOrderState
  from osmaxx.excerptexport.services.shortcuts import get_authenticated_api_client
  from osmaxx.utilities.shortcuts import Emissary
  
  
  def tracker(request, order_id):
      order = get_object_or_404(extraction_order.ExtractionOrder, pk=order_id)
      order.progress_url = request.GET['status']
      order.save()
      client = get_authenticated_api_client()
      client.update_order_status(order)
  
      emissary = Emissary(recipient=order.orderer)
  
      substitutions = dict(
          order_id=order.id,
          excerpt_name=order.excerpt_name,
          order_state=ExtractionOrderState.label(order.state),
      )
  
      if order.are_downloads_ready:
          message = _(
              'The extraction of the order #{order_id} "{excerpt_name}" has been finished.'
          ).format(**substitutions)
  
          finished_email_subject = _('Extraction Order #{order_id} "{excerpt_name}" finished').format(**substitutions)
          finished_email_body = _(
              'The extraction order #{order_id} "{excerpt_name}" has been finished and is ready for retrieval.'
          ).format(**substitutions)
  
          finished_email_body += '\n\n' + '\n'.join(
              file.content_type + ': ' + request.build_absolute_uri(file.get_absolute_url()) for file in order.output_files.all()  # noqa
          )
  
          emissary.success(message)
          emissary.inform_mail(subject=finished_email_subject, mail_body=finished_email_body)
      elif order.state == ExtractionOrderState.FAILED:
          message = _(
              'The extraction order #{order_id} "{excerpt_name}" has failed. Please try again later.'
          ).format(**substitutions)
  
          finished_email_subject = _('Extraction Order #{order_id} "{excerpt_name}" failed').format(**substitutions)
          finished_email_body = _(
              'The extraction order #{order_id} "{excerpt_name}" could not be completed, please try again later.'
          ).format(**substitutions)
  
          emissary.error(message)
          emissary.inform_mail(subject=finished_email_subject, mail_body=finished_email_body)
      else:
          message = _('Extraction order #{order_id} "{excerpt_name}" is now {order_state}.').format(**substitutions)
          emissary.info(message)
      response = HttpResponse('')
      response.status_code = 200
      return response
  
new_contents: from django.http import HttpResponse
  from django.shortcuts import get_object_or_404
  from django.utils.translation import gettext as _
  
  from osmaxx.excerptexport.models import extraction_order, ExtractionOrderState
  from osmaxx.excerptexport.services.shortcuts import get_authenticated_api_client
  from osmaxx.utilities.shortcuts import Emissary
  
  
  def tracker(request, order_id):
      order = get_object_or_404(extraction_order.ExtractionOrder, pk=order_id)
      order.progress_url = request.GET['status']
      order.save()
      client = get_authenticated_api_client()
      client.update_order_status(order)
  
      emissary = Emissary(recipient=order.orderer)
  
      substitutions = dict(
          order_id=order.id,
          excerpt_name=order.excerpt_name,
          order_state=ExtractionOrderState.label(order.state),
      )
  
      if order.are_downloads_ready:
          message = _(
              'The extraction of the order #{order_id} "{excerpt_name}" has been finished.'
          ).format(**substitutions)
  
          finished_email_subject = _('Extraction Order #{order_id} "{excerpt_name}" finished').format(**substitutions)
          finished_email_body = _(
              'The extraction order #{order_id} "{excerpt_name}" has been finished and is ready for retrieval.'
          ).format(**substitutions)
  
          finished_email_body += '\n\n' + '\n'.join(
              '{gis_format}: {download_url}'.format(
                  gis_format=file.content_type,
                  download_url=request.build_absolute_uri(file.get_absolute_url()),
              ) for file in order.output_files.all()
          )
  
          emissary.success(message)
          emissary.inform_mail(subject=finished_email_subject, mail_body=finished_email_body)
      elif order.state == ExtractionOrderState.FAILED:
          message = _(
              'The extraction order #{order_id} "{excerpt_name}" has failed. Please try again later.'
          ).format(**substitutions)
  
          finished_email_subject = _('Extraction Order #{order_id} "{excerpt_name}" failed').format(**substitutions)
          finished_email_body = _(
              'The extraction order #{order_id} "{excerpt_name}" could not be completed, please try again later.'
          ).format(**substitutions)
  
          emissary.error(message)
          emissary.inform_mail(subject=finished_email_subject, mail_body=finished_email_body)
      else:
          message = _('Extraction order #{order_id} "{excerpt_name}" is now {order_state}.').format(**substitutions)
          emissary.info(message)
      response = HttpResponse('')
      response.status_code = 200
      return response
  
subject: use string interpolation instead of concatenation #346