docs: def set_title(field, render_kw=None):
      """
      Returns *render_kw* with *min* and *max* set if required.
  
      If the field got a *description* but no *title* key is set, the *title* is
      set to *description*.
  
      """
      if render_kw is None:
          render_kw = {}
      if 'title' not in render_kw and getattr(field, 'description'):
          render_kw['title'] = '{}'.format(field.description)
      return render_kw