old_contents: /* eslint-disable import/no-commonjs */
  
  const webpack = require('webpack')
  
  const baseConfig = {
    entry: './src/index.js',
    module: {
      rules: [
        {
          test: /\.js$/,
          use: 'babel-loader',
          exclude: /node_modules/,
        },
      ],
    },
    output: {
      library: 'ReduxMost',
      libraryTarget: 'umd',
    },
    externals: {
      most: {
        root: 'most',
        commonjs2: 'most',
        commonjs: 'most',
        amd: 'most',
      },
      redux: {
        root: 'Redux',
        commonjs2: 'redux',
        commonjs: 'redux',
        amd: 'redux',
      },
    },
    resolve: {
      extensions: ['.js'],
      mainFields: ['module', 'main', 'jsnext:main'],
    },
  }
  
  const devConfig = {
    ...baseConfig,
    output: {
      ...baseConfig.output,
      filename: './dist/redux-most.js',
    },
    plugins: [
      new webpack.EnvironmentPlugin({
        'NODE_ENV': 'development',
      }),
    ],
  }
  
  const prodConfig = {
    ...baseConfig,
    output: {
      ...baseConfig.output,
      filename: './dist/redux-most.min.js',
    },
    plugins: [
      new webpack.EnvironmentPlugin({
        'NODE_ENV': 'production',
      }),
      new webpack.optimize.UglifyJsPlugin({
        compress: {
          screw_ie8: true,
          warnings: false,
        },
        comments: false,
      }),
    ],
  }
  
  module.exports = [devConfig, prodConfig]
  
new_contents: /* eslint-disable import/no-commonjs */
  
  const webpack = require('webpack')
  
  const baseConfig = {
    entry: './src/index.js',
    module: {
      rules: [
        {
          test: /\.js$/,
          use: 'babel-loader',
          exclude: /node_modules/,
        },
      ],
    },
    output: {
      library: 'ReduxMost',
      libraryTarget: 'umd',
    },
    externals: {
      most: {
        root: 'most',
        commonjs2: 'most',
        commonjs: 'most',
        amd: 'most',
      },
      redux: {
        root: 'Redux',
        commonjs2: 'redux',
        commonjs: 'redux',
        amd: 'redux',
      },
    },
    resolve: {
      extensions: ['.js'],
      mainFields: ['module', 'main', 'jsnext:main'],
    },
  }
  
  const devConfig = {
    ...baseConfig,
    output: {
      ...baseConfig.output,
      filename: './dist/redux-most.js',
    },
    plugins: [
      new webpack.EnvironmentPlugin({
        'NODE_ENV': 'development',
      }),
    ],
  }
  
  const prodConfig = {
    ...baseConfig,
    output: {
      ...baseConfig.output,
      filename: './dist/redux-most.min.js',
    },
    plugins: [
      new webpack.EnvironmentPlugin({
        'NODE_ENV': 'production',
      }),
      new webpack.optimize.UglifyJsPlugin({
        compress: {
          screw_ie8: true,
          warnings: false,
        },
        comments: false,
      }),
    ],
  }
  
  // This is a not well documented feature of Webpack.
  // When exporting an array Webpack 2 will run
  // multiple times... once for each config in the
  // array (synchronously from first to last). This
  // is what allows us to use multiple configs in
  // a single file.
  module.exports = [devConfig, prodConfig]
  
subject: Add a comment about Webpack config array exports for clarity