code: function(name, source, options) {
        // check if already defined
        if (this._loader.importPromises[name])
          throw new TypeError('Module is already loading.');
        return createImportPromise(this, name, new Promise(asyncStartLoadPartwayThrough({
          step: 'translate',
          loader: this._loader,
          moduleName: name,
          moduleMetadata: options && options.metadata || {},
          moduleSource: source,
          moduleAddress: options && options.address
        })));
      }
docs: 26.3.3.2