docs: function minmaxValidator(value, testValue, validityName, limit, compareFunction) {
                  if (!angular.isUndefined(testValue) && limit) {
                      if (!ngModelCtrl.$isEmpty(value) && compareFunction) {
                          return testValue;
                      } else {
                          return value;
                      }
                  }
                  else {
                      if (!limit) {
                          ngModelCtrl.$setValidity(validityName, !compareFunction);
                      }
                      return value;
                  }
              }