return this.select(function(value) { return value != null; 
return this.map(function(value, index) { return iterator(collections.pluck(index)); 
    return this.select(function(value) {      return value != null;    });
6462	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/6462/110aa6ceb19f486c3930285023b66d3f23fdf6c4/prototype.js/buggy/wp-includes/js/prototype.js