text: const fs = require('fs-extra');
  const concat = require('concat');
  
  (async function build() {
    const files = [
      './dist/todo-header/runtime-es2015.js',
      './dist/todo-header/polyfills-es2015.js',
      './dist/todo-header/scripts.js',
      './dist/todo-header/main-es2015.js'
    ];
  
    await fs.ensureDir('elements');
    await concat(files, 'elements/todo-header.js');
    await fs.copyFile(
      './dist/todo-header/styles.css',
      'elements/todo-header.styles.css'
    );
  })();
  