code: function createClass() {
      var parent = null,
          properties = slice.call(arguments, 0);
  
      if (typeof properties[0] === 'function') {
        parent = properties.shift();
      }
      function klass() {
        this.initialize.apply(this, arguments);
      }
  
      klass.superclass = parent;
      klass.subclasses = [ ];
  
      if (parent) {
        subclass.prototype = parent.prototype;
        klass.prototype = new subclass;
        parent.subclasses.push(klass);
      }
      for (var i = 0, length = properties.length; i < length; i++) {
        addMethods(klass, properties[i], parent);
      }
      if (!klass.prototype.initialize) {
        klass.prototype.initialize = emptyFunction;
      }
      klass.prototype.constructor = klass;
      return klass;
    }
docs: Helper for creation of "classes"
  @method createClass
  @memberOf fabric.util