I was curious what PyCharm would handle that. Here's a screenshot: http://imgur.com/IvwG5
Basically it will complain if neither Car or Tree have a DriveOnExpressway method, but it's fine if one of them does -- the warning goes away if I uncomment the method. So there's ways to fall through the safety net, but lots of things it will catch.
(In Javascript, it's looser -- it only flags a potential problem if "DriveOnExpressway" isn't defined at all in the file.)
Basically it will complain if neither Car or Tree have a DriveOnExpressway method, but it's fine if one of them does -- the warning goes away if I uncomment the method. So there's ways to fall through the safety net, but lots of things it will catch.
(In Javascript, it's looser -- it only flags a potential problem if "DriveOnExpressway" isn't defined at all in the file.)