docs: def form_group_wrapped(f):
      """
      Wrap a field within a bootstrap form-group. Additionally sets has-error
  
      This decorator sets has-error if the field has any errors.
      """
      @wraps(f)
      def wrapped(self, field, *args, **kwargs):
          classes = ['form-group']
          if field.errors:
              classes.append('has-error')
  
          html = """<div class="{classes}">{rendered_field}</div>""".format(
              classes=' '.join(classes),
              rendered_field=f(self, field, *args, **kwargs)
          )
          return HTMLString(html)
  
      return wrapped