mapOutput method
      
O?
mapOutput(
    
    
- E? out
Implementation
O? mapOutput(E? out) {
  if (outputFilter != null) {
    try {
      return outputFilter!(out);
    } catch (e, s) {
      print('<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<');
      print(e);
      print(s);
      print('>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>');
      return null;
    }
  } else {
    return out as O?;
  }
}