play method
Plays CSS animation.
initialDelayAn initial delay, before start transitions.callbackCallback to be called after transition and set of_finalProperties.
NOTE: Should return null if isNotValid.
Implementation
@override
Future<void> play({Duration? initialDelay, AnimationCallback? callback}) {
var plays = _configs
.map((c) => c.play(initialDelay: initialDelay, callback: callback))
.whereType<Future<void>>()
.toList();
return Future.wait(plays);
}