code: function(arr, comparator) {
  			var lookup = [];
  			return arr.filter(function(item) {
  				var val = comparator ? comparator(item) : item;
  				if (lookup.indexOf(val) < 0) {
  					lookup.push(val);
  					return true;
  				}
  			});
  		}
docs: ************************
  Utility belt
  ************************