old_contents: from django.core.urlresolvers import reverse
  from django.forms import model_to_dict
  from django.http.response import HttpResponseRedirect, HttpResponse
  from django.shortcuts import render
  
  from common.models import Student
  
  from sell.forms import PersonalDataForm
  
  
  def index(request):
      return HttpResponseRedirect(reverse('sell.views.personal_data'))
  
  
  def personal_data(request):
      if request.method == 'POST':
          form = PersonalDataForm(request.POST)
          if form.is_valid():
              request.session['personal_data'] = model_to_dict(form.save(commit=False))
              return HttpResponseRedirect(reverse('sell.views.books'))
      else:
          if request.session['personal_data']:
              form = PersonalDataForm(instance=Student(**request.session['personal_data']))
          else:
              form = PersonalDataForm()
      return render(request, 'sell/personal_data.html', {'form': form})
  
  
  def books(request):
      return HttpResponse("Hello, world!")
new_contents: from django.core.urlresolvers import reverse
  from django.forms import model_to_dict
  from django.http.response import HttpResponseRedirect, HttpResponse
  from django.shortcuts import render
  
  from common.models import Student
  
  from sell.forms import PersonalDataForm
  
  
  def index(request):
      return HttpResponseRedirect(reverse('sell.views.personal_data'))
  
  
  def personal_data(request):
      if request.method == 'POST':
          form = PersonalDataForm(request.POST)
          if form.is_valid():
              request.session['personal_data'] = model_to_dict(form.save(commit=False))
              return HttpResponseRedirect(reverse('sell.views.books'))
      else:
          if 'personal_data' in request.session:
              form = PersonalDataForm(instance=Student(**request.session['personal_data']))
          else:
              form = PersonalDataForm()
      return render(request, 'sell/personal_data.html', {'form': form})
  
  
  def books(request):
      return HttpResponse("Hello, world!")
subject: Fix KeyError in Provide personal data form