LightningOutExample.page

<apex:page >
    <apex:includeLightning />
    <div id="lightning" />
    <button type="button" onclick="callLightningEvent();">Call Lightning Code From VF</button>
    <script>        
        window.onload = function() {
           $Lightning.use("c:LightningOutExampleApp", function() {               
              var comapp=$Lightning.createComponent("c:LightningOutExample", 
              {},             
              "lightning",
              function(component) {
              	console.log('Lightning out -->Component has been loaded.');
                $A.eventService.addHandler({ "event": "c:lightningAppExternalEvent", "handler" : myFunctionFromVisualforce });                
              });              
            });            
        }

        function callLightningEvent(){
        	var lightningEvent = $A.get("e.c:lightningAppEvent");
            lightningEvent.setParams({'data':{'TestDataKey':'TestDataValue'}});
            lightningEvent.fire();
        }

        function myFunctionFromVisualforce (event){
        	console.log('This message is from visualforce function');
        	console.log('Data which is coming from lightning component',event.getParam('data'));
        	debugger;
        }
    </script>
</apex:page>

Hello sir,
when i am calling callLightningEvent function. its giving below error plz look it, sir. plz guide me where i m doing wrong sir. waiting for ur reply sir. thnx in advance.

aura_prod.js:853 Uncaught TypeError: Cannot read property 'setParams' of undefined
throws at https://practice-org-dev-ed--c.ap4.visual.force.com/apex/LightningOutExampleVF?core.apexpages.request.devconsole=1:26:28 TypeError: Cannot read property 'setParams' of undefined
at callLightningEvent (LightningOutExampleVF?core.apexpages.request.devconsole=1:26)
at HTMLButtonElement.onclick (LightningOutExampleVF?core.apexpages.request.devconsole=1:9)