foo

      def sequence_hash
        {
          "ws_start"          => "delete_filesystem",
          "delete_filesystem" => { next: next_step },
          "type"              => { next: "size" },
          "size"              => { next: new_blk_device_step1, finish: :finish }
        }.merge(new_blk_device_steps)
      end
      
      def next_step
        if cond
          controller.thing = foo
          skip_back :type
          :size
        else
          :type
        end
      end