Parsing one data type to another

Parsing.dart

void main() {
  //final one = int.parse('one'); //error
  final two = double.parse('2.2'); //successful 
  final three = int.tryParse('one'); //null
  final four = double.tryParse('4.5'); //successful
  final one = int.parse('3');
  
  print('''
$two
$three
$four
  ''');
  
  print(parsingInteger(one));
}

int parsingInteger(Object n) {
  return n as int;
}