code: def post(self, *args, **kwargs):
          
          prev_step = self.request.POST.get('wizard_prev_step', None)
          if prev_step and prev_step in self.get_form_list():
              self.storage.current_step = prev_step
              return redirect(self.url_name, step=prev_step)
          return super(NamedUrlWizardView, self).post(*args, **kwargs)
docs: Do a redirect if user presses the prev. step button. The rest of this
          is super'd from FormWizard.