code: function exampleScripts() {
    return gulp.src( './examples/index.js' )
      .pipe( webpackStream( {
        module: {
          rules: [ {
            use: [ {
              loader: 'babel-loader?cacheDirectory=true',
              options: {
                presets: [ [ 'env', {
                  targets: {
                    browsers: config.supportedBrowsers
                  },
                  debug: true
                } ] ]
              }
            } ],
            exclude: /node_modules/
          } ]
        },
        output: {
          filename: 'example.js'
        },
      }, webpack ) )
      .pipe( gulp.dest( config.BUILD ) );
  }
docs: TODO: Consolidate build scripts to call one helper function like in cfgov-refresh. 
  Generate main bundle.
  @returns {PassThrough} A source stream.