text: {
    if (process.env.CIRCLE_PR_NUMBER) {
      version += "+pr." + process.env.CIRCLE_PR_NUMBER;
    }
  
    const typeofPlugin = require("babel-plugin-transform-es2015-typeof-symbol")
      .default;
  
    const preset2015 = require("babel-preset-es2015").default();
  
    const es2015WithoutTypeof = {
      plugins: preset2015.plugins.filter(plugin => plugin !== typeofPlugin)
    };
    const config = {
      module: {
        rules: [
          {
            test: /\.js$/,
            loader: "babel-loader",
            options: {
              babelrc: false,
              presets: [es2015WithoutTypeof, require("babel-preset-stage-0")]
            }
          }
        ]
      },
      node: {
        fs: "empty",
        module: "empty",
        net: "empty"
      },
      output: {
        filename: filename,
        library: libraryName,
        libraryTarget: "umd"
      },
      plugins: [
        new webpack.DefinePlugin({
          "process.env.NODE_ENV": '"production"',
          BABEL_VERSION: JSON.stringify(
            require("babel-core/package.json").version
          ),
          VERSION: JSON.stringify(version)
        }),
        new webpack.NormalModuleReplacementPlugin(
          /debug\/node/,
          "debug/src/browser"
        ),
        new webpack.optimize.ModuleConcatenationPlugin()
      ],
      resolve: {
        plugins: [new RootMostResolvePlugin(__dirname + "/../../../", true)]
      }
    };
  
    if (libraryName !== "Babel") {
      config.externals = {
        "babel-standalone": "Babel"
      };
    }
  
    return webpackStream(config, webpack);
  }
  