Add missing import.

biscuit/apps/chronos/views.py

@@ -5,7 +5,7 @@ from typing import Optional
 from django.contrib.auth.decorators import login_required
 from django.db.models import Max, Min
 from django.http import HttpRequest, HttpResponse
-from django.shortcuts import redirect, render
+from django.shortcuts import get_object_or_404, redirect, render
 from django.urls import reverse
 from django.utils.translation import ugettext as _
 from django_tables2 import RequestConfig