code: function extractSass(files) {
  
          // note:  The way we're setting up webpack here seems a bit of a hack:
          //
          // Although the setup creates two bundles seperating the js and css as desired,
          // it's also producing an extra styles.js file which we're throwing away/ignoring.
          // The alternative, more supported way of things, is to leave the css inline
          // within js and let the styles plugin add the css at runtime to the html page.
          // At the moment keeping with the extracted css as:
          // 1. more familar to angular 1 developers (?)
          // 2. maintains backwards compatibility with the existing apps that expects
          //    the css to be delivered to the browser as a seperate file
  
          const filename = env.prod ? `${libraryName}.min.css` : `${libraryName}.css`;
          const extractor = new ExtractTextPlugin(filename);
          let loader;
          if (env.debug || env.prod) {
              loader = 'css-loader?sourceMap!sass-loader?sourceMap';
          } else {
              loader = 'css-loader!sass-loader';
          }
          return {
              entry: {
                  styles: files
              },
              module: {
                  rules: [
                      {
                          test: /\.scss$/,
                          loader: extractor.extract(loader),
                          include: files
                      }
                  ]
              },
              plugins: [
                  extractor
              ]
          };
      }
docs: Extracts styles into a seperate bundle