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Solve the following problem using Python, implementing the functions described below, one line at a time
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<USER_TASK:>
Description:
 def post(self, request):
 """ Save the user and profile, login and send the right signals. """


        if request.user.is_authenticated():
            return self.error_to_response(request, dict(
                error=_("You are already logged in.")))

        try:
            user, profile, client = self.get_session_data(request)
        except KeyError:
            return self.error_to_response(request, dict(
                error=_("A social profile is missing from your session.")))
        
        form = self.get_form()(request.POST, request.FILES,
            initial=self.get_initial_data(request, user, profile, client))
        
        if not form.is_valid():
            additional_context = self.get_context(request, user, profile, client)
            return self.render_to_response(dict({'form': form}, **additional_context))
        
        user, profile = form.save(request, user, profile, client)
        
        user = profile.authenticate()
        
        self.send_connect_signal(request, user, profile, client)
        
        self.login(request, user)
        
        self.send_login_signal(request, user, profile, client)
        
        self.delete_session_data(request)
        
        return HttpResponseRedirect(self.get_next(request))