How to use the gulp.start function in gulp

gulp.task('build:webapp', function (cb) { // eslint-disable-line no-unused-vars
  buildDirectory = webappBuildDirectory;
  gulp.start('build');
});

.on('end', x => {
                gutil.log(`compile finished: ${dest}`)
                if (isSubDir(relpath, ['common', 'web'])) gulp.start('browserify:web')
                if (isSubDir(relpath, ['common', 'titanium'])) gulp.start('browserify:ti')
            })
    })

gulp.watch(path.join(conf.paths.src, '/app/assets/images/favicons/**/*'), function(event) {
    gulp.start('favicons');
  });

soundcloudBundler.on('update', function(){
    gulp.start('soundcloud');
  });
  gulp.watch(paths.static, ['static']);

      gulpWatch('app/**/*.ts', function (){ gulp.start('tslint'); });
      buildBrowserify({ watch: true }).on('end', done);

watch([path.watch.vendors], function (event, cb) {
    gulp.start('vendors:build');
  });
  watch([path.watch.fonts], function (event, cb) {

gulp.task('default', () => {
  gulp.start('make')
  gulp.start('todo')
  gulp.start('watch')
})

gulp.task('clean', function () {
    gulp.start( 'clean:js', 'clean:css');
});

watch(paths.app.stylesAll, function () {
    gulp.start('styles', 'inject-css');
  });