code: def empowerment(iface, priority=0):
      
      def _deco(cls):
          cls.powerupInterfaces = (
              tuple(getattr(cls, 'powerupInterfaces', ())) +
              ((iface, priority),))
          implementer(iface)(cls)
          return cls
      return _deco
docs: Class decorator for indicating a powerup's powerup interfaces.
  
      The class will also be declared as implementing the interface.
  
      @type iface: L{zope.interface.Interface}
      @param iface: The powerup interface.
  
      @type priority: int
      @param priority: The priority the powerup will be installed at.