     @first    = first
     @second   = second
     @flip     = !!flip
+    return this
 
   # The map of conversions from CoffeeScript to JavaScript symbols.
   CONVERSIONS =

    @base       = base
    @properties = props or []
    @[tag]      = true if tag

  children: ['base', 'properties']


      function ctor() { this.constructor = child; }
      ctor.prototype = parent.prototype;
      child.prototype = new ctor;
      for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; }
      child.__super__ = parent.prototype;
      return child;
    }
