knockout.js - which function will be consider as view model in knockout js -

i new in knockout js. please see below code , tell me function consider view model ?

there 2 function 1 cartline , other 1 cart.............which function consider view model ?

see code ko.applybindings(new cart());

apply binding pointing cart function.......so mean cart() consider view model ? if yes should cartline() ? child or nested view model ?

looking guidance. code taken jsfiddle http://jsfiddle.net/3bu6nybk/15/

var cartline = function () {           var self = this;           self.products = ko.observablearray(_products);           self.product = ko.observable(1);           self.price = ko.observable(1);           self.quantity = ko.observable(1);              self.product.subscribe(function(item){               if(!item)               {                   self.price(0);                  self.quantity(0);                  return;               }              self.price(item.price);              self.quantity(item.quantity);           });            self.subtotal = ko.computed(function () {                return self.price() * self.quantity();           },self);       };        var cart = function () {           // stores array of lines, , these, can work out grandtotal           var self = this;           self.lines = ko.observablearray([new cartline()]); // put 1 line in default           self.formatcurrency = formatcurrency;        }; 

if enclose of code in variable this:

var viewmodel = {     //your code here } 

then call apply bindings so:

ko.applybindings(new viewmodel()); 

everything in viewmodel.

see link more info: http://knockoutjs.com/documentation/observables.html