code: def login_oauth2_user(valid, oauth):
      
      if valid:
          oauth.user.login_via_oauth2 = True
          _request_ctx_stack.top.user = oauth.user
          identity_changed.send(current_app._get_current_object(),
                                identity=Identity(oauth.user.id))
      return valid, oauth
docs: Log in a user after having been verified.