Matrixdef: Can I limit a loop by one iteration?

Is there (already) a way to add a button similar to what BeginIter-EndIter does, but to have it only fire one time?

E.g. a button such as “Add a feature” that would only allow you to add exactly one feature?

Is it “Button”, maybe?

It looks like iterables use “button” so that’s probably the right thing to try. Unfortunately the BeginIter-EndIter lets you set a minimum number, but I can’t find a way to set a maximum.

It’s possible that this use case wasn’t considered. Note that this whole language (Dreillshak Normal Form) is defined in, which could be changed…