rem: return '#<Hash:{' + this.map(function(pair) { return pair.map(Object.inspect).join(': '); }).join(', ') + '}>'; 
add: return this.select(function(value) { return value != undefined || value != null; }); 
context:     return '#<Hash:{' + this.map(function(pair) {      return pair.map(Object.inspect).join(': ');    }).join(', ') + '}>';
meta: 3974	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/3974/af9adbf17404d887f31369756326b0109da7ae2b/prototype.js/buggy/root/static/js/prototype.js