code: function(parentClass, constructor) {
  	// inherits methods from parent class
  	constructor.prototype = Object.create(parentClass.prototype);
  	
  	// inherits methods from Subscribable class 
  	for(var key in Subscribable.prototype) {
  		constructor.prototype[key] = Subscribable.prototype[key];
  	}
  	
  	constructor.prototype.constructor = constructor;
  	constructor.prototype._keepHot = true;
  	
  	return constructor;
  }
docs: Create model class with a subscribable interface.