title: Django HTTPResponseRedirect & Reverse with optional parameter
body: <p>How do I use Django's Reverse with an optional parameter for info? I keep on getting </p>
  
  <p>views.py:</p>
  
  <pre><code>def cartForm(request, prod):
      if request.method=="POST":
          quantity = request.POST.get('quantity', False)
          if quantity:
              add_to_cart(request, prod, quantity)
              return HttpResponseRedirect(reverse("cart"))
          #if no quantity indicated, display error message
          return HttpResponseRedirect(reverse('products.views.info', kwargs={'prod': prod, 'error':True}))
  
  def info(request, prod, error=False):
      prod = Product.objects.get(id=prod)
      return render(request, "products/info.html", dict(product = prod, error=error))
  </code></pre>
  
  <p>urls.py:</p>
  
  <pre><code>url(r'^(?P&lt;prod&gt;\d+)/', "products.views.info", name='info'),
  </code></pre>
  
  <p>I keep on getting the following error:</p>
  
  <pre><code>Reverse for 'products.views.info' with arguments '()' and keyword arguments '{'prod': u'2', 'error': True}' not found. 1 pattern(s) tried: ['products/(?P&lt;prod&gt;\\d+)/']
  </code></pre>