A page is a small TEA app on its own.

It has the typical Msg, Model, init, update, subscriptions and view. It differs from a normal application in a few ways:

• The init and update functions return Effect Shared.Msg Msg instead of Cmd Msg.

• The init function takes a unique flags argument that is the output of the page match function (see Spa.addPublicPage).

• The view function returns a View Msg, which can be whatever you define.

Create a static page that has no states, only a view

Create a "sandboxed" page that cannot communicate with the outside world.

It is the page equivalent of a sanboxed program

Create a page that can communicate with the outside world.

It is the page equivalent of a element program

Set the message to pass when the flags change. If not set, the 'init' function is called, resulting in a complete reset of the page model.