Flatten "last"?

Hey everyone - very simple thing i am trying to accomplish, there may already be a component for it.

I would like to have a simple component or cluster that will flatten only the last branch of a data structure... essentially a path mapper that does the following:

{a;b;c;d;e} ---> {a;b;c;d}

{a;b;c;d} ---> {a;b;c}

{a;b;c} ---> {a;b}

etc.

any ideas?