jspm_packages/system-csp-production.src.js
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
      })));
    }
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
      })));
    }
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 } ) ) ) ; }
26.3.3.2
26 . 3 . 3 . 2