{% macro render_field(field, help=None) %}
  <div class="form-group{% if field.errors %} has-error{% endif %}">
    <label class="control-label" for="{{ field.id }}">{{ field.label.text }}</label>
    {{ field(class="form-control", **kwargs)|safe }}
    {% if field.errors %}
    <ul class="errors">
      {% for error in field.errors %}
      <li>{{ error }}</li>
      {% endfor %}
    </ul>
    {% elif help %}
    <span class="help-block">{{ help }}</span>
    {% endif %}
  </div>
{% endmacro %}