old_contents: import browserify from 'browserify';
  import gulp from 'gulp';
  import source from 'vinyl-source-stream';
  import buffer from 'vinyl-buffer';
  import uglify from 'gulp-uglify';
  import babel from 'gulp-babel';
  import sourcemaps from 'gulp-sourcemaps';
  import gutil from 'gulp-util';
  import rename from 'gulp-rename';
  import babelify from 'babelify';
  import es3ify from 'gulp-es3ify';
  import rimraf from 'rimraf';
  
  const paths = {
    sourceBrowser: 'lib/src/browser.js',
    sourceNode: ['lib/src/*.js', '!lib/src/browser.js', '!lib/src/data.js'],
    sourceBin: 'lib/bin/*.js',
    destBrowser: 'build/browser/',
    destNode: 'build/node/',
    destBin: 'build/bin',
  };
  
  gulp.task('default', ['build:browser', 'build:node', 'build:bin']);
  
  gulp.task('build:browser', ['clean:browser'], () =>
    browserify(paths.sourceBrowser, { debug: true })
      .transform(babelify, { sourceMaps: true })
      .bundle()
      .pipe(source('transliteration.js'))
      .pipe(buffer())
      .pipe(sourcemaps.init({ loadMaps: true }))
        .pipe(es3ify())
        .pipe(gulp.dest(paths.destBrowser))
        .pipe(rename('transliteration.min.js'))
        .pipe(uglify())
        .on('error', gutil.log)
      .pipe(sourcemaps.write('./'))
      .pipe(gulp.dest(paths.destBrowser))
      .pipe(gutil.noop())
  );
  
  gulp.task('build:node', ['clean:node'], () =>
    gulp.src(paths.sourceNode)
      .pipe(babel())
      .pipe(gulp.dest(paths.destNode))
  );
  
  gulp.task('build:bin', ['clean:bin'], () =>
    gulp.src(paths.sourceBin)
      .pipe(babel())
      .pipe(rename({ extname: '' }))
      .pipe(gulp.dest(paths.destBin))
  );
  
  gulp.task('clean:browser', cb => rimraf('build/browser/*', cb));
  
  gulp.task('clean:node', cb => rimraf('build/node/*', cb));
  
  gulp.task('clean:bin', cb => rimraf('build/bin/*', cb));
  
new_contents: import browserify from 'browserify';
  import gulp from 'gulp';
  import source from 'vinyl-source-stream';
  import buffer from 'vinyl-buffer';
  import uglify from 'gulp-uglify';
  import babel from 'gulp-babel';
  import sourcemaps from 'gulp-sourcemaps';
  import gutil from 'gulp-util';
  import rename from 'gulp-rename';
  import babelify from 'babelify';
  import es3ify from 'gulp-es3ify';
  import rimraf from 'rimraf';
  
  const paths = {
    sourceBrowser: 'lib/src/browser.js',
    sourceNode: ['lib/src/*.js', '!lib/src/browser.js', '!lib/src/data.js'],
    sourceBin: 'lib/bin/*.js',
    destBrowser: 'build/browser/',
    destNode: 'build/node/',
    destBin: 'build/bin',
  };
  
  gulp.task('default', ['build:browser', 'build:node', 'build:bin']);
  
  gulp.task('build:browser', ['clean:browser'], () =>
    browserify(paths.sourceBrowser, { debug: true })
      .transform(babelify)
      .bundle()
      .pipe(source('transliteration.js'))
      .pipe(buffer())
      .pipe(sourcemaps.init({ loadMaps: true }))
        .pipe(es3ify())
        .pipe(gulp.dest(paths.destBrowser))
        .pipe(rename('transliteration.min.js'))
        .pipe(uglify())
        .on('error', gutil.log)
      .pipe(sourcemaps.write('./'))
      .pipe(gulp.dest(paths.destBrowser))
      .pipe(gutil.noop())
  );
  
  gulp.task('build:node', ['clean:node'], () =>
    gulp.src(paths.sourceNode)
      .pipe(babel())
      .pipe(gulp.dest(paths.destNode))
  );
  
  gulp.task('build:bin', ['clean:bin'], () =>
    gulp.src(paths.sourceBin)
      .pipe(babel())
      .pipe(rename({ extname: '' }))
      .pipe(gulp.dest(paths.destBin))
  );
  
  gulp.task('clean:browser', cb => rimraf('build/browser/*', cb));
  
  gulp.task('clean:node', cb => rimraf('build/node/*', cb));
  
  gulp.task('clean:bin', cb => rimraf('build/bin/*', cb));
  
subject: correct way to call babelify