var users = {
'barney': { 'age': 36, 'active': true },
'fred': { 'age': 40, 'active': false },
'pebbles': { 'age': 1, 'active': true }
};
_.findLastKey(users, function(o) { return o.age < 40; });
// => returns 'pebbles' assuming `_.findKey` returns 'barney'
// The `_.matches` iteratee shorthand.
_.findLastKey(users, { 'age': 36, 'active': true });
// => 'barney'
// The `_.matchesProperty` iteratee shorthand.
_.findLastKey(users, ['active', false]);
// => 'fred'
// The `_.property` iteratee shorthand.
_.findLastKey(users, 'active');
// => 'pebbles'