get is not defined when trying to extends JSONSerializer

I try to define my custom serializer by extending DS.JSONSerialzer.

I pick the serialize function without modifications but when i run Ember,i get this error:

ReferenceError: get is not defined

This is my code :

import DS from 'ember-data';

export default DS.JSONSerializer.extend({
    serialize: function(record, options) {
        var json = {};
        if (options && options.includeId) {
            var id = get(record, 'id');
            if (id) {
                json[get(this, 'primaryKey')] = id;
            }
        }

        record.eachAttribute(function(key, attribute) {
            this.serializeAttribute(record, json, key, attribute);
        }, this);
        record.eachRelationship(function(key, relationship) {
            if (relationship.kind === 'belongsTo') {
                this.serializeBelongsTo(record, json, relationship);
            } else if (relationship.kind === 'hasMany') {
                this.serializeHasMany(record, json, relationship);
            }
        }, this);
        return json;
    },
});

I didn't change any code. This is the original. Why get is suddenly undefined? It's imported in ligne 1 in the original file JSONSerialiser

Can you help me?