def build_clone_callback(callback)
      case callback
      when Proc
        callback
      when Symbol
        ->(original, clone) {
          original.send(callback, clone) if original.respond_to?(callback, true)
        }
      end
    end
def build_clone_callback(callback)
      case callback
      when Proc
        callback
      when Symbol
        ->(original, clone) {
          original.send(callback, clone) if original.respond_to?(callback, true)
        }
      end
    end
We ensure that the passed callback is actually callable on the object
 we're cloning. This is needed for associations because deep_cloneable
 calls the callback for every associated object.