Snippet 3: More nullable types!

main.dart

// Type parameters for generics can also be nullable or
// non-nullable. Try using question marks to correct the
// type declarations of `aNullableListOfStrings` and
// `aListOfNullableStrings`:

void main() {
  List<String> aListofStrings = ['one', 'two', 'three'];
  List<String> aNullableListOfStrings;
  List<String> aListofNullableStrings = ['one', null, 'three'];
  
  print('aListofStrings is $aListofStrings.');
  print('aNullableListOfStrings is $aNullableListOfStrings.');
  print('aListofNullableStrings is $aListofNullableStrings.');
}