[Zope] How do I count children?

[J. Atwood]

So In ZUBB (my discussion product) I want to be able to show how many
replies there have been to any one main topic. All replies are 'children' of
the main post and when I state it with

<dtml-tree branches=children>
    Stuff
</dtml-tree>

It works and knows that each message is a child of the message.

When in go through a searchResult to list the message I want to  show many
replies there are to that message.

Q: How do I count the 'children' of any one onject?

Thanks,
J