static _getRequestID() {
    let id = this.nextRequestID,
      obj = {};

    obj.promise = new Promise((resolve, reject) => {
      obj.resolve = resolve;
      obj.reject = reject;
    });

    this._callbackData[id] = obj;

    return id;
  }
/**
   * Gets the next request ID and sets up the Promise resolve/reject callbacks
   *
   * @returns {string} - The request ID
   * @private
   */
Gets the next request ID and sets up the Promise resolve/reject callbacks
@returns {string} - The request ID
@private
Gets the next request ID and sets up the Promise resolve / reject callbacks @returns { string } - The request ID @private
static _getRequestID() {
    let id = this.nextRequestID,
      obj = {};
    obj.promise = new Promise((resolve, reject) => {
      obj.resolve = resolve;
      obj.reject = reject;
    });
    this._callbackData[id] = obj;
    return id;
  }
static _getRequestID ( ) { let id = this . nextRequestID , obj = { } ; obj . promise = new Promise ( ( resolve , reject ) => { obj . resolve = resolve ; obj . reject = reject ; } ) ; this . _callbackData [ id ] = obj ; return id ; }
Gets the next request ID and sets up the Promise resolve/reject callbacks
 @returns {string} - The request ID
 @private
Gets the next request ID and sets up the Promise resolve / reject callbacks @returns { string } - The request ID @private