How to use the terriajs/buildprocess/runWebpack.js function in terriajs

function(done) {
        var runWebpack = require("terriajs/buildprocess/runWebpack.js");
        var webpack = require("webpack");
        var webpackConfig = require("./buildprocess/webpack.config.js")(true);

        checkForDuplicateCesium();

        runWebpack(webpack, webpackConfig, done);
    }
);

function(done) {
        var runWebpack = require("terriajs/buildprocess/runWebpack.js");
        var webpack = require("webpack");
        var webpackConfig = require("./buildprocess/webpack.config.js")(false);

        checkForDuplicateCesium();

        runWebpack(
            webpack,
            Object.assign({}, webpackConfig, {
                plugins: [
                    new webpack.optimize.UglifyJsPlugin({ sourceMap: true }),
                    new webpack.optimize.OccurrenceOrderPlugin()
                ].concat(webpackConfig.plugins || [])
            }),
            done
        );
    }
);