Get the first key in the map. Returns null
if the map is empty.
K firstKey() { if (_root == null) return null; return _first.key; }
© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dartlang.org/stable/2.0.0/dart-collection/SplayTreeMap/firstKey.html