How to use the webpack-config.Config function in webpack-config

import webpack from 'webpack'
import { Config } from 'webpack-config'
import { BundleAnalyzerPlugin } from 'webpack-bundle-analyzer'

module.exports = new Config()
  .extend({
    './webpack.development.js': function(config) {
      delete config.debug
      // delete config.devtool
      delete config.output.pathinfo
      delete config.devServer
      delete config.entry.server
      delete config.entry.app
      delete config.plugins
      delete config.entry.vendors
      config.entry[process.env.LIBRARY_NAME] = process.env.SRC_ENTRY

      return config
    }
  })
  .merge({

var Config = require("webpack-config").Config;

module.exports = new Config().extend("conf/node.es6.config.js").merge({
    devtool: "#source-map",
    output: {
        pathinfo: true
    },
    watch: true,
    devServer: {
        stats: {
            chunks: false
        }
    }
});

var Config = require("webpack-config").Config;

module.exports = new Config().extend("conf/web.es5.config.js").merge({
    devtool: "#source-map",
    output: {
        pathinfo: true
    },
    watch: true,
    devServer: {
        stats: {
            chunks: false
        }
    }
});

var webpack = require("webpack");
var Config = require("webpack-config").Config;
var CompressionPlugin = require("compression-webpack-plugin");

module.exports = new Config().extend("conf/web.es6.config.js").merge({
    devtool: "#source-map",
    plugins: [
        new webpack.optimize.OccurrenceOrderPlugin(),
        new CompressionPlugin({
            asset: "[path].gz[query]",
            algorithm: "gzip",
            test: /\.js$|\.css$|\.html$/
        })
    ]
});

var webpack = require('webpack');
var WebpackConfig = require('webpack-config').Config;
var path = require('path');

var BUILD_DIR = path.resolve(__dirname, 'dist');
var APP_DIR = path.resolve(__dirname, 'src/client/app');
var JSNEXT_MAIN = path.resolve(__dirname, require('./package.json')['jsnext:main']);

var config = new WebpackConfig().merge({
    //entry: JSNEXT_MAIN.toString(),
    output: {
        path: BUILD_DIR,
        filename: 'stack-es2015-modules.js'
    },
    devtool: "inline-source-map",
    module : {
        loaders : [
            {
                test: /\.(jsx|js)$/,
                exclude : [
                    /node_modules/
                ],
                loader : 'babel-loader'
            }
        ]