code: function (config) {
                  if (typeof config !== 'object') {
                      throw new Error('You must provide a valid configuration object to the config setter.');
                  }
                  // combine config with default
                  var mergedConfig = Object.assign({}, config);
                  // add config to map
                  this._config = new Map(Object.entries(mergedConfig));
              }
docs: set the configuration of a class instance
  @method config
  @param {object} config object of configurations