var Person = basilisk.makeStruct(['name', 'age']),
    example = new Person({ name: 'Joe', age: 32 }),
    older = example.with_('age', example.age + 2);

// we make a quick alias, to reduce clutter in the code.
var b$ = basilisk.query,

    Person = basilisk.makeStruct(['name', 'age', 'addresses']),
    Address = basilisk.makeStruct(['city', 'country']),

    example = new Person({
        name: 'Joe',
        age: 32, 

        addresses = basilisk.Vector.from([
            new Address({ city: 'London', country: 'United Kingdom' }),
            new Address({ city: 'Cape Town', country: 'South Africa' })
        ])
    }),
    example2, example3;

// first we create a new object, with a US address added.

example2 = b$.swap(example, ['addresses'], function (current) {
    return current.push(new Address({ city: 'Boston', country: 'USA' }));
});

// and if we have to replace a part of that new address.

example3 = b$.replace(example2, ['addresses', b$.at(2), 'city'], 'New York');