code: function buildPostbid() {
    var fileContent = fs.readFileSync('./build/postbid/postbid-config.js', 'utf8');
  
    return gulp.src('./integrationExamples/postbid/oas/postbid.js')
      .pipe(replace('\[%%postbid%%\]', fileContent))
      .pipe(gulp.dest('build/postbid/'));
  }
docs: This task creates postbid.js. Postbid setup is different from prebid.js More info can be found here http://prebid.org/overview/what-is-post-bid.html