Brep.UnjoinEdges - clarification?

What does the last line mean as far as output? Seems a bit confusing.

Seems to indicate the input brep is not modified, how then do I get the brep with the unjoined edges?

Edit - a small test here indicates that the original is not modified, but the return is indeed the modified brep(s). That last line in the help doc just seems very non-sequitur…