code: function() {
      this._super.apply(this, arguments);
      this._transpilerCache = {};
      this.toFormat = esperanto[formatToFunctionName[this.format]];
  
      if (this.format === 'umd' && !this.bundleOptions) {
        throw new Error(umdMesssage);
      }
    }
docs: /*
  Called when ES6Modules is `new`ed. Creates a new cache for transpiled files
  and determine what method to delegate to esperanto for transpiling files.