"A value getter of type `Nothing`. The expression `nothing`
 is formally assignable to any type, but produces an 
 exception when evaluated.
 
 (This is most useful for tool-generated implementations of
 `formal` members.)"​
​throws (`class AssertionError`, 
        "when evaluated")
​tagged("Basic types")
​shared Nothing nothing {
    "nothing may not be evaluated"​
    assert (false);
}
​