To find the first and last grouped result, a developer should be able to use 'first' and 'last' variables in a TAL repeat scenario

In `RepetitionInfo` there should also be [support for `first` and `last`], which are for grouped/duplicate results.  Support needs to be added.

[support for `first` and `last`]: https://zope.readthedocs.io/en/latest/zopebook/AppendixC.html#the-following-information-is-available-from-the-repeat-variable