Gulp task definition helper so all gulp tasks can have descriptions for `gulp -T`.

gulpfile.js

'use strict';
const exec = require('child_process').exec;

// Quick shortcut for shortcomings in `gulp.task` API:
// 1. `gulp.task` doesn't accept a description, has to be a prop on the function.
// 2. Since description has to be on the task function, it's harder to add a
//    description to tasks whose functions were created by a helper (e.g.
//    `gulp.series` or `gulp.parallel`) since you didn't define the functions
//    they return.
function gulpTask(name, desc, fn) {
  gulp.task(name, fn);
  gulp.task(name).unwrap().description = desc;
}

gulpTask(
  'ls_js',
  'Task for listing Javascript files',
  done => exec('ls *.js', done)
);

gulpTask(
  'ls_html',
  'Task for listing HTML files',
  done => exec('ls *.html', done)
);

gulpTask(
  'ls_all',
  'Task for listing JS and HTML files',
  gulp.series('ls_js', 'ls_html')
);