text: from django.core.files.storage import get_storage_class
  from django.shortcuts import redirect
  from django.utils.cache import add_never_cache_headers
  
  from storages.backends.s3boto3 import S3Boto3Storage
  from wagtail.contrib.modeladmin.options import (ModelAdmin, ModelAdminGroup,
                                                  modeladmin_register)
  from wagtail.core import hooks
  from wagtail.documents import get_document_model
  from wagtail.documents.models import document_served
  
  from tbx.sign_up_form.models import SignUpFormPageResponse
  
  from .models import GoogleAdGrantApplication
  
  
  class GoogleAdGrantApplicationModelAdmin(ModelAdmin):
      model = GoogleAdGrantApplication
      menu_label = 'Ad Grant Applications'
      menu_icon = 'date'
      menu_order = 600
      add_to_settings_menu = False
      list_display = ('date', 'name', 'email')
  
  
  class SignUpFormPageResponseModelAdmin(ModelAdmin):
      model = SignUpFormPageResponse
      menu_label = 'Sign-Up Form Page Submissions'
      menu_icon = 'date'
      menu_order = 600
      add_to_settings_menu = False
      list_display = ('date', 'email')
  
  
  class SubmissionsModelAdminGroup(ModelAdminGroup):
      menu_label = 'Form Submissions'
      menu_icon = 'folder-open-inverse'  # change as required
      menu_order = 600
      items = (SignUpFormPageResponseModelAdmin, GoogleAdGrantApplicationModelAdmin)
  
  
  modeladmin_register(SubmissionsModelAdminGroup)
  
  
  @hooks.register('before_serve_document', order=100)
  def serve_document_from_s3(document, request):
      # Skip this hook if not using django-storages boto3 backend.
      if not issubclass(get_storage_class(), S3Boto3Storage):
          return
  
      # Send document_served signal.
      document_served.send(sender=get_document_model(), instance=document,
                           request=request)
  
      # Get direct S3 link.
      file_url = document.file.url
  
      # Generate redirect response and add never_cache headers.
      response = redirect(file_url)
      del response['Cache-control']
      add_never_cache_headers(response)
      return response
  