weX5如何绑定KO对象

define(function(require){ 
   var $ = require("jquery"); 
   var justep = require("$UI/system/lib/justep");
   var Model = function(){
           this.callParent(); 
           this.myText = justep.Bind.observable("bind!");  
   }; 
   Model.prototype.button2Click = function(event){  
           this.myText.set(false);  
   };  
       
   return Model;  
});