subtract method
Implementation
void subtract(Duration duration) {
_durationLeft -= duration;
if (_durationLeft.isNegative) {
throw Exception('Duration cannot be negative');
}
if (isDone) _onDone();
}
void subtract(Duration duration) {
_durationLeft -= duration;
if (_durationLeft.isNegative) {
throw Exception('Duration cannot be negative');
}
if (isDone) _onDone();
}