fblocked(n) on macOS
The text 61162baddd60, as Mac OS X 10.1.5, Mac OS X 10.1.4, Mac OS X 10.1.3, Mac OS X 10.1.2, Mac OS X 10.1.1, Mac OS X 10.1, Mac OS X 10.0.4, Mac OS X 10.0 shipped it.
Test whether the last input operation exhausted all available input