var list = new Expiry(['bread','milk','eggs']); // or just Expiry(...) without the "new"
list.expires(302460*1000);
// ['bread','milk','eggs']

list.expires();
// April 29, 2014

// ten minutes later
list.expired() // false

// ...30 days after that
list.expired() // true

// alternate init in constructor
var dataModel = { ... };
dataModel = Expiry(dataModel, 1000*180);

var dataModel = Expiry.rm(dataModel);
dataModel.expires()
// TypeError: Object #