title: Why Django raising ValueError?
body: <p>This is my view.py file under my project folder.
  When I add a value in ToDo list it raises this error?</p>
  
  <blockquote>
    <p>The view my_day.views.index didn't return an HttpResponse object. It returned None instead.</p>
  </blockquote>
  
  <p><strong>views.py</strong></p>
  
  <pre><code>from django.shortcuts import render, redirect
  from .models import List
  from .form import ListForm
  from django.contrib import messages
  
  
  # Create your views here.
  def index(request):
      if request.method == "POST":
          form = ListForm(request.POST or None)
  
          if form.is_valid():
              form.save()
              all_items = List.objects.all
              messages.success(request, ('Task Added'))
              return render(request, 'index.html', {'all_items': all_items})
  
       else:
  
          all_items = List.objects.all
          return render(request, 'index.html', {'all_items': all_items})
  </code></pre>