old_contents: 'use strict';
  
  var gulp = require('gulp');
  var babel = require('gulp-babel');
  var del = require('del');
  var lint = require('gulp-eslint');
  var plumber = require('gulp-plumber');
  var rename = require('gulp-rename');
  
  var srcJS = './src/foo.js';
  
  // Tasks
  // ---------------------------------------------------------
  gulp.task('clean', function () {
    del(['./foo.js']);
  });
  
  gulp.task('lint', function () {
    return gulp.src(srcJS)
      .pipe(plumber())
      .pipe(lint())
      .pipe(lint.format())
      .pipe(lint.failOnError());
  });
  
  gulp.task('build', ['clean', 'lint'], function () {
    return gulp.src(srcJS)
      .pipe(plumber())
      .pipe(babel())
      .pipe(rename('index.js'))
      .pipe(gulp.dest('./'));
  });
  
  gulp.task('watch', function () {
    gulp.watch(srcJS, ['lint']);
  });
  
  // default task
  // -----------------------------------------------
  gulp.task('default', ['clean', 'lint', 'watch']);
  
new_contents: 'use strict';
  
  var gulp = require('gulp');
  var babel = require('gulp-babel');
  var del = require('del');
  var lint = require('gulp-eslint');
  var plumber = require('gulp-plumber');
  var rename = require('gulp-rename');
  
  var config = {
    src: './src/server.js'
  };
  
  // Tasks
  // ---------------------------------------------------------
  gulp.task('clean', function () {
    del(['./dist']);
  });
  
  gulp.task('lint', function () {
    return gulp.src(config.src)
      .pipe(plumber())
      .pipe(lint())
      .pipe(lint.format())
      .pipe(lint.failOnError());
  });
  
  gulp.task('build', ['clean', 'lint'], function () {
    return gulp.src(config.src)
      .pipe(plumber())
      .pipe(babel())
      .pipe(rename('index.js'))
      .pipe(gulp.dest('./'));
  });
  
  gulp.task('watch', function () {
    gulp.watch(config.src, ['lint']);
  });
  
  // default task
  // -----------------------------------------------
  gulp.task('default', ['clean', 'lint', 'watch']);
  
subject: Set gulpfile config vars