Null class final
The reserved word
null denotes an object that is the sole instance of
Null class is the only class which does not implement
It is a compile-time error for a class to attempt to extend or implement
The language contains a number of specialized operators for working with
null value. Examples:
e1! // Throws if e1 is null. e2 ?? e3 // Same as e2, unless e2 is null, then use value of e3 x ??= e4 // Same as x unless x is null, then same as `x = e4`. e5?.foo() // call `foo` on e5, unless e5 is null. [...? e6] // spreads e6 into the list literal, unless e6 is null.