operator [] method
The value for the given key
, or null
if key
is not in the map.
Some maps allow null
as a value.
For those maps, a lookup using this operator cannot distinguish between a
key not being in the map, and the key being there with a null
value.
Methods like containsKey or putIfAbsent can be used if the distinction
is important.
Implementation
@override
String? operator [](Object? key) => _environment[key];