Defining a class as a type with Google Closure
If I have code like this:

    var x = {};
    
    /**
     * @constructor 
     * ???
     */
    x.MyClass = function() {
    
    };
    
    x.MyClass.prototype = {
    
       hello: "Hello World",
    
       /**
        * @return {x.MyClass}
        */
       y: function() {
          console.log(this.hello);
          return this;
       }
    
    };

Closure tells me that this is `x.MyClass` is not a defined type. How can I make it a defined type?
Defining a class as a type with Google Closure
===

If I have code like this:

    var x = {};
    
    /**
     * @constructor 
     * ???
     */
    x.MyClass = function() {
    
    };
    
    x.MyClass.prototype = {
    
       hello: "Hello World",
    
       /**
        * @return {x.MyClass}
        */
       y: function() {
          console.log(this.hello);
          return this;
       }
    
    };

Closure tells me that this is `x.MyClass` is not a defined type. How can I make it a defined type?