code: function umd(cb) {
    const env = process.env.NODE_ENV || 'development';
    const output = env === 'development' ? './build' : './dist';
  
    rollup.rollup({
      input: './src/dom7.js',
      plugins: [resolve(), buble()],
    }).then((bundle) => {
      return bundle.write({
        strict: true,
        file: `${output}/dom7.js`,
        format: 'umd',
        name: 'Dom7',
        sourcemap: env === 'development',
        sourcemapFile: `${output}/dom7.js.map`,
        banner,
      });
    }).then(() => {
      if (env === 'development') {
        if (cb) cb();
        return;
      }
      gulp.src('./dist/dom7.js')
        .pipe(sourcemaps.init())
        .pipe(uglify())
        .pipe(header(banner))
        .pipe(rename('dom7.min.js'))
        .pipe(sourcemaps.write('./'))
        .pipe(gulp.dest('./dist/'))
        .on('end', () => {
          if (cb) cb();
        });
    });
  }
docs: UMD DIST