code: function(callback) {
  
  				// optimize as many times as the user wants
  				async.timesSeries(options.optimize.input.svgo, function(i, next) {
  
  					// tell the user that we’re optimizing
  					grunt.log.writeln('Optimizing inputs with SVGO (pass ' + (i + 1) + ' of ' + options.optimize.input.svgo + ')…');
  
  					// asynchronously loop through the files
  					async.each(task.files, function(file, callback2) {
  
  						// create a promise to optimize the SVGs
  						promise = optimizeSVGO(file, options);
  
  						// when that promise is finished, print the results onscreen
  						// (if we’re being verbose)
  						// and continue onwards
  						promise.done(function(results) {
  							if (results) {
  								grunt.verbose.ok(results);
  							}
  							callback2(null);
  						});
  
  					}, next);
  
  				}, callback);
  
  			}
docs: optimize inputs - SVGO