title: Deleting files in a gulp task
body: <p>I have a gulp task in which I want to take some source files and copy them to <code>build/premium</code> and <code>build/free</code> and then remove some extra files from
  <code>build/free</code>.</p>
  
  <p>My attempt at that was doing this:</p>
  
  <pre><code>gulp.task("build", ["clean"], function () {
    gulp.src(["src/*", "!src/composer.*", "LICENSE"])
      .pipe(gulp.dest("build/premium"))
      .pipe(del(["build/free/plugins/*", "!build/free/plugins/index.php"]))
      .pipe(gulp.dest("build/free"));
  });
  </code></pre>
  
  <p>Which results in an error:</p>
  
  <pre><code>TypeError: dest.on is not a function
      at DestroyableTransform.Stream.pipe (stream.js:45:8)
      at Gulp.&lt;anonymous&gt; (/Users/gezim/projects/myproj/gulpfile.js:9:6)
  </code></pre>
  
  <p>How do I accomplish this the deleting port? Is there a better way altogether to do this?</p>