This is a directive for NIT (Número de Identificación Tributaria, some sort of Tax ID in Guatemala).
You may use it as a bower component:
bower install verynicetech/nt-nit-validator
Or alternatively:
bower install angular-nit-validator
You may as well download the javascript file and use it yourself.
First of all, you need to include the script in your HTML file.
<script type="text/javascript" src="bower_components/angular-nit-validator/src/angular-nit-validator.js"></script>
Then, you need to modify your app.js file to include the dependency.
angular.module('yourModuleName', ['nicetech.directives'])
Finally, add it as an attribute to your inputs or components that depend on ng-model.
<input type="text" ng-model="nit" nit />
Cheers!