How to use the jsonld.normalize function in jsonld

var toTriples = function (input, graph, cb) {
    var rval = null;

    // normalize input
    jsonld.normalize(input, {}, function (err, normalized) {
        if (err)
            cb(err);
        else {
            var parseTerm = function (term) {
                if (term.type === 'blank node') {
                    return {'blank': term.value};
                } else if (term.type === 'IRI') {
                    return {'token': 'uri', 'value': term.value};
                } else if (term.type === 'literal') {
                    if (term.language != null) {
                        return {'literal': '"' + term.value + '"@' + term.language};
                    } else if (term.datatype !== null) {
                        return {'literal': '"' + term.value + '"^^<' + term.datatype + ">"};
                    } else {
                        return {'literal': '"' + term.value + '"'};

jsonld.normalize(jsonldExpected, opts, function (err, norm1) {
    if (err) {
      return callback(err);
    }
    jsonld.normalize(jsonldGot, opts, function (err, norm2) {
      if (err) {
        return callback(err);
      }
      try {
        assert.deepEqual(norm1, norm2);
        return callback();
      } catch (e) {
        return callback(e);
      }
    });
  });
}

* normalize() test
 */
jsonld.normalize(doc, (err, res) => {
    log(res);
});

jsonld.normalize(doc, {algorithm: 'URDNA2015', expansion: false}, (err, res) => {
    log(res);
});

jsonld.normalize(doc)
.then((res) => {
    log(res);
});

jsonld.normalize(doc, {expansion: false})
.then((res) => {
    log(res);
});

/**
 * fromRDF() test
 */
jsonld.fromRDF(docNQuads, (err, res) => {
    log(res);
});

jsonld.fromRDF(docNQuads, {format: 'application/n-quads'}, (err, res) => {
    log(res);
});

jsonld.fromRDF(docRDF)

log(res);
});

jsonld.frame(doc, frame, {requireAll: true})
.then((res) => {
    log(res);
});

/**
 * normalize() test
 */
jsonld.normalize(doc, (err, res) => {
    log(res);
});

jsonld.normalize(doc, {algorithm: 'URDNA2015', expansion: false}, (err, res) => {
    log(res);
});

jsonld.normalize(doc)
.then((res) => {
    log(res);
});

jsonld.normalize(doc, {expansion: false})
.then((res) => {
    log(res);
});

/**
 * fromRDF() test
 */

function assertEqualRdf (jsonldExpected, jsonldGot, options, callback) {
  var opts = {
    base: options.base,
    format: 'application/nquads'
  };
  jsonld.normalize(jsonldExpected, opts, function (err, norm1) {
    if (err) {
      return callback(err);
    }
    jsonld.normalize(jsonldGot, opts, function (err, norm2) {
      if (err) {
        return callback(err);
      }
      try {
        assert.deepEqual(norm1, norm2);
        return callback();
      } catch (e) {
        return callback(e);
      }
    });
  });
}

return callback(this._error(doc, resp.statusCode));
    }

    var ctxUrl = this.url('');

    //check if the server could satisfy the option and if so return
    if ( ((opts.profile === 'expanded') && Array.isArray(doc)) ||
         ((opts.profile === 'flattened') && ('@context' in doc) && ('@graph' in doc)) ||
         ((opts.profile === 'compacted') && ('@context' in doc))
       ) {

      if (opts.normalize) {
        if (doc['@context'] === SchemaOrgIo.contextUrl) {
          doc['@context'] = ctxUrl;
        }
        jsonld.normalize(doc, {format: 'application/nquads'}, callback);
      } else {
        callback(null, doc);
      }
      return;
    }

    //the server could not satisfy the option we suppose we got a JSON doc
    var ctxUrlFromLink;
    if (resp.headers.link){
      var links = jsonld.parseLinkHeader(resp.headers.link);
      if ('http://www.w3.org/ns/json-ld#context' in links){
        ctxUrlFromLink = links['http://www.w3.org/ns/json-ld#context'].target;
      };
    }

    if (!ctxUrlFromLink && !doc['@context']){

function(err,doc) {
        if (err) {
          callback(err);
          return;
        }
        jsonld.normalize(doc, function(err,doc) {
          if (err) {
            callback(err);
            return;
          }
          doc = doc['@default'];
          var object;
          for (var n = 0, l = doc.length; n < l; n++) {
            var triple = doc[n];
            var subject = triple.subject.value;
            var predicate = triple.predicate.value;
            object = triple.object;
            if (object.type === 'IRI' || object.type === 'blank node') {
              object = object.value;
            } else if (object.type === 'literal') {
              var val = '"' + object.value + '"';
              if (object.language)

doc['@context'] = ctxUrl;
    }

    function _next(err, pdoc) {
      if (err) return callback(err);

      //reverse @context transfo
      if (ctx && pdoc['@context'] === ctxUrl) {
        pdoc['@context'] = ctx;
      }

      callback(null, pdoc);
    };

    if (opts.normalize) {
      jsonld.normalize(doc, {format: 'application/nquads'}, _next);
    } else if (opts.profile === 'flattened') {
      jsonld.flatten(doc, doc['@context'], _next);
    } else if (opts.profile === 'expanded') {
      jsonld.expand(doc, {expandContext: doc['@context']}, _next);
    } else {
      jsonld.compact(doc, doc['@context'], _next);
    }

  }.bind(this));
};