code: function registerTask( task ) {
  		grunt.registerMultiTask( task.name, task.help, function () {
  			var done = this.async();
  			if ( ensureSketchtool() ) {
  				var options = this.options();
  
  				var commands = [];
  				this.files.forEach( function( file ) {
  					file.src.filter( function ( src ) {
  						var command = createCommand( task, src, file.dest, options );
  						if ( command ) {
  							commands.push( command );
  						}
  					} );
  				});
  				
  				async.eachLimit( commands, numCPUs, function ( command, next ) {
  					executeCommand( command, next );
  				}, done );
  			} else {
  				done(false);
  			}
  		} );
  	}
docs: Internal helper functions.