{%if hasError %}
<p><strong><font color="red"> {{hasError}} </font></strong></p>
{%endif%}
<form method="POST" action="{{url_for('after_form')}}">
  <select name="prenom">
    <option value="Mickey">Mickey Mouse</option>
    <option value="Tintin">Tintin</option>
    <option value="Valjean">Jean Valjean</option>
    <option value="Homer">Homer Simpson</option>
  </select>
  <input type="submit" value="Soumettre" />
</form>