code: function(attr, value) {
            var self = this,
                result = {},
                error;
  
            if(_.isObject(attr)){
              _.each(attr, function(value, key) {
                error = self.preValidate(key, value);
                if(error){
                  result[key] = error;
                }
              });
  
              return _.isEmpty(result) ? undefined : result;
            }
            else {
              return validateAttr(this, attr, value, _.extend({}, this.attributes));
            }
          }
docs: Check whether or not a value, or a hash of values passes validation without updating the model