<script src="tom.js"></script>
<script src="tonny.js"></script>
<script src="scott.js"></script>
<script>
  speak();
 /* This will create a naming conflict as
    scott, tonny and tom, all use the same function */
</script>

var tom  = {};
(function(namespace) {
    namespace.speak = function() {
      console.log("I am Tom !");
    };
})(tom );

var tonny  = {};
(function() {
    this.speak =  function() {
      console.log("I am Tonny  !")
    };
}).apply(tonny );

var scott  = {};
(function() {
  var speakSoftly = function() {
      console.log("I am Scott !")
  };
  this.speak = function() {
     speakSoftly();
  };
}).call(scott );


tom.speak();
tonny.speak();
scott.speak();
scott.speakSoftly; // speakSoftly is local to IIFE block