code: function getWebpackConfig( env = {}, argv = {} ) {
  	env.WP = true;
  
  	if ( 'theme' === argv.source ) {
  		argv.entry = path.join( __dirname, 'blank-theme' );
  		argv[ 'output-path' ] = path.join( __dirname, 'blank-theme', 'dist' );
  		argv[ 'output-filename' ] = 'blank-theme.js';
  	} else {
  		argv.entry = path.join( __dirname, 'full-site-editing-plugin' );
  		argv[ 'output-path' ] = path.join( __dirname, 'full-site-editing-plugin', 'dist' );
  		argv[ 'output-filename' ] = 'full-site-editing-plugin.js';
  	}
  
  	const webpackConfig = getBaseWebpackConfig( env, argv );
  
  	return {
  		...webpackConfig,
  		watch: isDevelopment,
  		devtool: isDevelopment ? 'inline-cheap-source-map' : false,
  	};
  }
docs: Return a webpack config object
  
  Arguments to this function replicate webpack's so this config can be used on the command line,
  with individual options overridden by command line args.
  
  @see {@link https://webpack.js.org/configuration/configuration-types/#exporting-a-function}
  @see {@link https://webpack.js.org/api/cli/}
  
  @param  {object}  env                           environment options
  @param  {object}  argv                          options map
  @param  {object}  argv.source                   "plugin" or "theme"
  @return {object}                                webpack config