var Klass = new Class((function() {

  var private_method = function() {
     // bla bla bla
  };


return {

  initialize: function() {
     this.bla = 'bla';

     private_method('bla', 'bla', 'bla');

     // or in context of the object

     private_method.call(this, 'bla', 'bla', 'bla');
  }



}})());