gulp.task('sprite', function () {

  var spriteData = gulp.src('./public/img/sprites/*.png').pipe(spritesmith({
    imgName: 'sprite.png',
    cssName: 'sprite.less',
    imgPath: '../img/sprite.png',
    cssTemplate:"rem.template.handlebars"
  }));
 
  // Pipe image stream through image optimizer and onto disk 
  var imgStream = spriteData.img
    // DEV: We must buffer our stream into a Buffer for `imagemin` 
    // .pipe(buffer())
    // .pipe(imagemin())
    .pipe(gulp.dest('./public/img/'));
 
  // Pipe CSS stream through CSS optimizer and onto disk 
  var cssStream = spriteData.css
    // .pipe(csso())
    .pipe(gulp.dest('./app/less/'));
 
  // Return a merged stream to handle both `end` events 
  return merge(imgStream, cssStream);
});