ES2015 Angular directive definition with ngAnnotate annotation & ES2015 module format

directive.js

function appCompareTo(serviceOne, serviceTwo) {
    'ngInject'; // Note position of 'ngInject' annotation
    return {
        require: "ngModel",
        scope: {
            otherModelValue: "=appCompareTo"
        },
        link: link
    };

    function link(scope, element, attributes, ngModel) {
        ngModel.$validators.appCompareTo = function(modelValue) {
            serviceOne.methodA();
            serviceTwo.methodB();
            return modelValue == scope.otherModelValue;
        };

        scope.$watch("otherModelValue", function() {
            ngModel.$validate();
        });
    }
}

export default { directive: appCompareTo, name: 'appCompareTo' };