[plt-scheme] 299.105

>> ==> serialize: expects argument of type <serializable object>; given
>> #<procedure:43:2>
>
> The procedure on line 43 is `add-key', and procedures aren't
> serializable.
>
> Probably you meant for it to be a private method instead of a private
> field, and the same for `remove-key'. Changing the definitions to
>

Yes, I wanted them to be private methods. Now it works. Thanks a lot!

--Erich