code: def default_images_directory(type):
      
      server_config = Config.instance().get_section_config("Server")
      img_dir = os.path.expanduser(server_config.get("images_path", "~/GNS3/images"))
      if type == "qemu":
          return os.path.join(img_dir, "QEMU")
      elif type == "iou":
          return os.path.join(img_dir, "IOU")
      elif type == "dynamips":
          return os.path.join(img_dir, "IOS")
      else:
          raise NotImplementedError("%s node type is not supported", type)
docs: :returns: Return the default directory for a node type