Node.js SDK donot have get a specific document function

Question

This function only found in the Discovery Java SDK but not in the NodeJs SDK. Our project implement using NodeJs, so can anybody kindly help us to deal with it? Maybe NodeJs engineer can add below function code into the node_modules :\node_modules\watson-developer-cloud\discovery\v1.js.

 /**
 * Get a specific document
 * @param params
 * @param {String} params.environment_id environment guid for the collection
 * @param {string} params.collection_id the guid of the collection to delete
 * @param {string} params.document_id the guid of the document to get
 * @param callback
 * @return {ReadableStream|undefined}
 */
DiscoveryV1.prototype.getDocument = function(params, callback) {
    params = params || {};
    const parameters = {
        options: {
            url: '/v1/environments/{environment_id}/collections/{collection_id}/documents/{document_id}',
            method: 'GET',
            path: pick(params, ['environment_id', 'collection_id', 'document_id']),
            json: true
        },
        requiredParams: ['environment_id', 'collection_id', 'document_id'],
        defaultOptions: this._options
    };
    return requestFactory(parameters, callback);
};