rem: return this.select(function(value) { return value != null; 
add: return this.map(function(value, index) { return iterator(collections.pluck(index)); 
context:     return this.select(function(value) {      return value != null;    });
meta: 8886	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/8886/c1f8a57fb495053291d684e68f518dd14dfa0a6f/prototype.js/clean/js_test/prototype.js