anchor.diff:      end.
   
   
  +handle_user_action(#{body_qs:=#{action := request}} = ReqMap) ->
  +   request_credential(ReqMap); 
  +handle_user_action(#{body_qs:=#{action := revoke}} = ReqMap) ->
  +   revoke_credential(ReqMap); 
   handle_user_action(#{body_qs:=#{action := logout}, session:=Session} = ReqMap) ->
       ok = tts_session:close(Session),
       maps:put(cookie, clear, redirect_to(ep_main,ReqMap));
   handle_user_action(ReqMap) ->
       show_user_page(ReqMap).
  -
  -
  -show_user_page_or_redirect(#{session := Session}) ->
  -    show_user_page_or_redirect(tts_session:is_logged_in(Session),Session). 
  -show_user_page_or_redirect(true, Session) ->
  -    show_user_page(Session);
  -show_user_page_or_redirect(_, _) ->
  -    redirect_to(ep_main,#{}).
   
   
   request_credential(#{session := Session}) ->
  
positive.code:     redirect_to_auth_server(ReqMap);
  handle(#{path := ep_return} = ReqMap) ->
      login_user_with_authcode(ReqMap);
  handle(#{path := ep_main} = ReqMap) ->
      redirect_to_user_page_or_login(ReqMap);
  handle(#{path := ep_user, method := post} = ReqMap) ->
      handle_user_action(ReqMap);
  handle(#{path := ep_user, method := post, post_action := request } = ReqMap) ->
      request_credential(ReqMap);
  handle(#{path := ep_user, method := post, post_action := revoke } = ReqMap) ->
      revoke_credential(ReqMap);
  handle(#{path := ep_user, method := get} = ReqMap) ->
      show_user_page_or_redirect(ReqMap).
      
  
  redirect_to_auth_server(#{body_qs:=BodyQs} = ReqMap) ->
  
negative.code:     show_error_page(Error, ReqMap).
  
  
  show_select_page(ReqMap) ->
      {ok, OIDCList} = oidcc:get_openid_provider_list(),
      GetIdAndDesc = fun({Id, Pid}, List) ->
  