code: function performValidation(field) {
          return function(rule, cb) {
              var valueToBeValidated = kontx.args.fields[field._id],
                  validate = validator.get(rule);
  
              //Undefined values do not need to be validated unless the field is required
              if (rule.type === 'required' || !_.isUndefined(valueToBeValidated)) {
                  if (_.isArray(valueToBeValidated)) {
                      q.all(
                          _.map(valueToBeValidated, function(value) {
                              return validate(value, rule.options);
                          })
                      )
                          .then(
                              function() {
                                  cb();
                              },
                              function() {
                                  cb(createError(400, validationTemplate({
                                      label: field.label
                                  })));
                              }
                      );
                  } else {
                      validate(valueToBeValidated, rule.options)
                          .then(
                              function() {
                                  cb();
                              },
                              function() {
                                  cb(createError(400, validationTemplate({
                                      label: field.label
                                  })));
                              }
                      );
                  }
              } else {
                  cb();
              }
          };
      }
docs: Function actually tests the field for a specific validation rule.