In example, extract is not resolved?

So I was running this example:
`var parser = require('packet').createPacketizer(this);

parser.extract("length: b16, address: b32, name: b8z", function (object) {
console.log(object.length, object.address, object.name);
});
parser.parse([ 0x01, 0xFF, 0x01, 0x00, 0x00, 0x00, 0x01, 0x02, 0x00 ]);`
And was getting the error "unresolved function or method extract". I am unsure what is wrong with the example, and I am a novice, so any help would be greatly appreciated. Thanks!