How to use the UrlFetchApp class with node.js

I'm trying to use a Google Apps Script class, but I'm having trouble finding information on how to use the classes contained in Apps Scripts and running on the node.

Ex: converter.js

if (process.argv.length < 3) {
    console.log('Usage: node ' + process.argv[1] + ' FILENAME');
    process.exit(1);
}
// Read the file and print its contents.
var objects;
var fs = require('fs')
, filename = process.argv[2];

function print(item, index){
    var sourceLang = 'auto';
    var targetLang = 'pt';

    var sourceText = 'Traduzir';

    //var translatedText = LanguageApp.translate(item.mappings.default.default, sourceLang, targetLang);
    //console.log(translatedText);

    var url = "https://translate.googleapis.com/translate_a/single?client=gtx&sl=" 
    + sourceLang + "&tl=" + targetLang + "&dt=t&q=" + encodeURI(sourceText);

    var result = JSON.parse(UrlFetchApp.fetch(url).getContentText());

    translatedText = result[0][0][0];
    console.log(translatedText);
    // console.log(item.mappings.default.default);
    // console.log(item.mappings.default.short);
}

fs.readFile(filename, 'utf8', function(err, data) {
    if (err) throw err;
  //console.log('OK: ' + filename);
  objects = JSON.parse(data);

  objects.forEach(print);

  console.log(objects.length);
  //console.log(data);
});

When I run with the command:

node conversor.js math_digits.json

Result:

/home/alcance/Área de Trabalho/conversor/conversor.js:23
    var result = JSON.parse(UrlFetchApp.fetch(url).getContentText());
                            ^

ReferenceError: UrlFetchApp is not defined
    at print (/home/alcance/Área de Trabalho/conversor/conversor.js:23:26)
    at Array.forEach (native)
    at /home/alcance/Área de Trabalho/conversor/conversor.js:36:11
    at FSReqWrap.readFileAfterClose [as oncomplete] (fs.js:380:3)

I have a problem with this: