Rebuild Underscore's identity function

var _ = {};

Identity is probably the easiest one.  It will be useful later on when a function is required as an argument but not given.  

_.identity = function(val) {

  return val;

}

This simply returns whatever value it is given.  

If this confuses you, then these exercises are probably going to be way over your head.  Just sayin.. 

Here's an example:  

var test = _.identity("hello");

console.log(test);

The console will display = hello