Question on internals of mailbox built-in class

In reply to dave_59:

In reply to puranik.sunil@tcs.com:
You can in fact build your own mailbox class using a combination of semaphores and queues. Some people do this because they want to be able to “stuff” extra entries in the mailbox, or examine the other entries in the mailbox.
One thing you can’t do is create a type-less mailbox or extend an existing mailbox class that is type-less. The type-less mailbox is a legacy feature from the Vera language, which did not have parameterized classes. There is really no good reason to use it anymore.

Thanks Dave for the explanation. I am planning to write my own mailbox class. Can you please provide an example for me or link to it, if you have it already.
rgs,
-sunil