How to name template filter to remove duplicates from list?

[Manuel Jacob]

Original motivation: In one of my repositories, when merging from the 
development branch to the production branch, I’d like to list all 
branches that were merged into the development branch since the last 
merge from the development branch into the production branch. If a 
branch consists of multiple changesets or the branch was merged multiple 
times, the branch should not be listed multiple times (at least not in a 
row). There doesn’t seem to be a way to remove duplicates from a list 
with existing template filters.

While I have not decided whether I want to remove all duplicates or only 
adjacent ones, I think both would be useful as template filters, so I’d 
like to implement them. Even if I end up implementing only one, it’s 
good to keep the other in mind.

The Unix tool uniq removes only adjacent duplicates, which I found 
surprising at first. I wouldn’t find "uniq" a good name for any variant 
of the filter, since removing only adjacent duplicates might surprise 
users not knowing the Unix tool, and removing all duplicates might 
surprise users knowing the Unix tool.

The name "removeduplicates" is descriptive but quite long. It could take 
an argument to choose whether all or only adjacent duplicates should be 
removed. Examples:

"{'a\na\nb\na'|splitlines|removeduplicates}\n"
-> "a b"

"{removeduplicates('a\na\nb\na'|splitlines, onlyadjacent=False)}\n"
-> "a b"

"{removeduplicates('a\na\nb\na'|splitlines, onlyadjacent=True)}\n"
-> "a b a"

Any other ideas?