drop method
      
void
drop(
    
    
- T asset
Implementation
void drop(T asset) {
  _toPrune.add(asset);
  _pruneTimer?.cancel();
  if (isPruningEnabled) {
    _pruneTimer = Timer(pruneAfter, _prune);
  }
}void drop(T asset) {
  _toPrune.add(asset);
  _pruneTimer?.cancel();
  if (isPruningEnabled) {
    _pruneTimer = Timer(pruneAfter, _prune);
  }
}