No output if uglify method is called

[sunilw]

Calling this task results in nothing being written to the destination directory

gulp.task('compress', function () {
  return pipeline(
        gulp.src('./src/js/**.js'),
      uglify(),
        gulp.dest('./out')
  );
});

However, if the method 'uglify' is commented out, then files are written to the destination directory.

[terinjokes]

There's not enough details to troubleshoot this.