Has anyone used one of these www.minichainsaw.com ? Its a sort of chain saw cable with two handles. You drape it over the limb or small tree to be cut and pull on one handle and then the other. Looks like good aerobic exercise and would be quite a handy little deal for me to carry aroung for light brush work on my place.Not as bulky or heavy as a regular chain saw. Wonder if they stay sharp? Seems to me I remember seeing someone use one of these when I was a boy. Is this some forgotten tool that someone has reinvented?