Higher order functions are functions within a function.
When we use the setInterval() function we give it 2
arguments.  The first is a function and the second is a
callback.  With the setInterval function the second 
argument is the time interval.  The first argument is
not called, we let the setInterval function call it.
We use clearInterval with the terminate number to stop it.

With an annoymous function we set the first agrument as 
a function without a name.

setInterval(function(){
     console.log("This is an annoymous function");
     console.log("This is an example");
	}, 2000);