code: function(model, value, attr) {
        var indices, validators,
          validations = model.validation ? _.result(model, 'validation') || {} : {};
        // If the validations hash contains an entry for the attr
        if (_.contains(_.keys(validations), attr)) {
          return validateAttrWithOpenArray(model, attr, value, _.extend({}, model.attributes));
        } else {
          indices = extractIndices(attr);
          attr = stripIndices(attr);
          validators = getValidators(model, attr);
          return invokeValidator(validators, model, value, attr, _.extend({}, model.attributes), indices);
        }
      }
docs: Validates attribute without open array notation.