def homepage(request):
     title = "test"
     exp_list = costs.objects.all()
     def total_sum(exp_list.exp_sum):
         s = o
         for x in a:
             s += a
     return s
     return render_to_response("main.html", {'title': title, 'type_list': type_list, 'exp_list': exp_list, 's': s,},
context_instance=RequestContext(request))