How to append new element to moddle

I am using bpmn-moddle to create bpmn tag. in which i have created Task element and have added extension elements to it. Below is my code

moddle.fromXML(xmlStr, function(err, definitions) {

        // add a root element
        var bpmnProcess = moddle.create('bpmn:Process', { id: 'MyProcess_1'});
        definitions.get('rootElements').push(bpmnProcess);
        var bpmnTask 
        bpmnTask = moddle.create('bpmn:Task', {id: i})

        var extension = moddle.create('bpmn:ExtensionElements')
        var game = moddle.createAny('wootz:property',  'http://wootz', {name: "taleoUrl"})
        extension.get('values').push(game) 

})

I am using bpmn-moddle to create bpmn tag. in which i have created Task element and have added extension elements to it. Below is my code

moddle.fromXML(xmlStr, function(err, definitions) {

        // add a root element
        var bpmnProcess = moddle.create('bpmn:Process', { id: 'MyProcess_1'});
        definitions.get('rootElements').push(bpmnProcess);
        var bpmnTask 
        bpmnTask = moddle.create('bpmn:Task', {id: i})

        var extension = moddle.create('bpmn:ExtensionElements')
        var game = moddle.createAny('wootz:property',  'http://wootz', {name: "taleoUrl"})
        extension.get('values').push(game) 

})

I have created a custom element using moddle.createAny(). and i want to add this custom element to another custom element. Below is the function i want to perform.

var goal = moddle.createAny('propertysss',  'http://vendor', {})
var game = moddle.createAny('wootz:property',  'http://wootz', {name: "taleoUrl"})

game.push(goal)

For the above line i am getting the error as push is not a function. can anyone help on how to add custom element to another custom element in bpmn-moddle

How does your descriptor (json) file look like? You would have to add one to ensure your custom elements can be created.

How does your descriptor (json) file look like? You would have to add one to ensure your custom elements can be created.