docs: function(keypath, value, attributes) {
        var content = "";
        if (!attributes) { attributes = {}; }
        if (attributes.hidden_element !== false) {
          content += this.hidden(keypath, {'value': !value});
        }
        delete attributes['hidden_element'];
        content += this.radio(keypath, value, $.extend({type: 'checkbox'}, attributes));
        return content;
      }