code: def queryset(self, request, queryset):
  		
  		filter_args = {self._filter_arg_key: None}
  
  		if self.value() == "yes":
  			return queryset.exclude(**filter_args)
  		if self.value() == "no":
  			return queryset.filter(**filter_args)
docs: Return the filtered queryset based on the value provided in the query string.
  
  		source: https://docs.djangoproject.com/en/1.10/ref/contrib/admin/#django.contrib.admin.ModelAdmin.list_filter