title: using series and parallel tasks in gulp 4.0
body: <p>I am trying to manipulate text before a file is sent to browserify, and I am attempting to use gulp.series to do this. Here's how:</p>
  
  <pre><code>gulp.task('dev_urls', function() {
    gulp.src([ 'app/index.js' ])
        .pipe(...)
        .pipe(gulp.dest(...))
  
  gulp.task('build_dev',
    gulp.series('dev_urls', 'browserify', gulp.parallel('copy')))
  </code></pre>
  
  <p>When I execute the <code>build_dev</code> task using <code>gulp build_dev</code> from the command line, I am given this error:</p>
  
  <pre><code>/usr/local/lib/node_modules/gulp/bin/gulp.js:121
      gulpInst.start.apply(gulpInst, toRun);
                    ^
  
  TypeError: Cannot read property 'apply' of undefined
    at /usr/local/lib/node_modules/gulp/bin/gulp.js:121:19
    at doNTCallback0 (node.js:407:9)
    at process._tickDomainCallback (node.js:377:13)
    at Function.Module.runMain (module.js:477:11)
    at startup (node.js:117:18)
    at node.js:951:3
  </code></pre>
  
  <p>How can I get this to work?</p>
  
  <p>EDIT:
  I am getting that same error with this file:</p>
  
  <pre><code>var gulp = require('gulp');
  gulp.task('build_dev', function() {
    console.log(1);
  })
  </code></pre>