gulp 4 cannot find gulp.parallel | gulp.series

I use gulp 4, and there is an error showing “gulp.parallel is not a function”.

I am here. @mikestreety gulp -v show

CLI version 1.2.1
Local version 3.9.1

This is my gulpfile, I delete some code and these code will cause the same result.

var fs = require('fs');
var _path = require('path');
var gulp = require('gulp')
var newer = require('gulp-newer');
var modify = require('gulp-modify');
var uglify = require('gulp-uglify')
var cleanCSS = require('gulp-clean-css');
var htmlmin = require('gulp-htmlmin');
var imagemin  = require('gulp-imagemin');

gulp.task('default', gulp.parallel(function () {
    console.log('finish')
}))

[nirazul]

$ npm install --save-dev gulp …will get you 3.9.1

$ npm install gulpjs/gulp.git#4.0 --save-dev …did not work for me (zsh: no matches found), I had to write it in quotes:

$ npm install 'gulpjs/gulp.git#4.0' --save-dev …so you’ll get 4.0.alpha

[xcatliu]

Why don’t publish a 4.0-alpha version in npm?