How to use LoopCopy function in scripts?

In the documentation LoopCopy is described as Loop Copy will copy the contents of the previously active loop into the currently active loop.

Yet, when I put it in a script, it doesn't seem to do anything at all. (in fact, I cannot find it in the list of functions either)

Does it work somehow? Can you use it with any options?

Would really like to use it.