Flash message is informative. Why not add it?

app/templates/userpage_get.html

@@ -55,9 +55,9 @@
         <a class="btn btn-secondary" href="/reset" role="button" onclick="stopRead()">重设密码</a>
 
     </p>
-{#    {% for message in flashed_messages %}#} {# 根据user_service.userpage,取消了参数flashed_messages，因此注释了这段代码 #}
-{#        <div class="alert alert-warning" role="alert">Congratulations! {{ message }}</div>#}
-{#    {% endfor %}#}
+    {% for message in get_flashed_messages() %}
+       <div class="alert alert-warning" role="alert">{{ message }}</div>
+    {% endfor %}
 
         <button class="btn btn-success" id="load_next_article" onclick="load_next_article();Reader.stopRead()"> 下一篇 Next Article </button>
         <button class="btn btn-success" id="load_pre_article" onclick="load_pre_article();Reader.stopRead()" style="display: none"> 上一篇 Previous Article </button>

app/user_service.py

@@ -181,7 +181,11 @@ def user_mark_word(username):
         for word in request.form.getlist('marked'):
             lst.append((word, [get_time()]))
         d = pickle_idea2.merge_frequency(lst, lst_history)
+        if len(lst_history) > 999:
+            flash('You have way too many words in your difficult-words book. Delete some first.')
+        else:
             pickle_idea2.save_frequency_to_pickle(d, user_freq_record)
+            flash('Added %s.' % (', '.join(request.form.getlist('marked'))))
         return redirect(url_for('user_bp.userpage', username=username))
     else:
         return 'Under construction'