todomvc-updating.js

var state = freezer.get();

// this will replace app state for a new one
state.todos.push({
  model: {id: 1, title: 'Do this.', completed: false},
  ui: {status: 'ready', input: 'Do this.'}
});

// state variable is still unchanged,
// it is immutable
console.log( state.todos ); // []

// but the state has changed
state === freezer.get(); // false

// our data is in the new state
console.log( freezer.get().todos.length ); // 1