code: def reply(request, message_id, form_class=ComposeForm,
          template_name='django_messages/compose.html', success_url=None,
          recipient_filter=None, quote_helper=format_quote,
          subject_template=_(u"Re: %(subject)s"),):
      
      parent = get_object_or_404(Message, id=message_id)
  
      if parent.sender != request.user and parent.recipient != request.user:
          raise Http404
  
      if request.method == "POST":
          sender = request.user
          form = form_class(request.POST, recipient_filter=recipient_filter)
          if form.is_valid():
              form.save(sender=request.user, parent_msg=parent)
              messages.info(request, _(u"Message successfully sent."))
              if success_url is None:
                  success_url = reverse('messages_inbox')
              return HttpResponseRedirect(success_url)
      else:
          form = form_class(initial={
              'body': quote_helper(parent.sender, parent.body),
              'subject': subject_template % {'subject': parent.subject},
              'recipient': [parent.sender,]
              })
      return render(request, template_name, {
          'form': form,
      })
docs: Prepares the ``form_class`` form for writing a reply to a given message
      (specified via ``message_id``). Uses the ``format_quote`` helper from
      ``messages.utils`` to pre-format the quote. To change the quote format
      assign a different ``quote_helper`` kwarg in your url-conf.