anchor.diff:  /**
    * Abstract parser that parses a list of things in some way.
    */
  -abstract class _ListParser extends Parser {
  +abstract class ListParser extends Parser {
   
     final List<Parser> _parsers;
   
  -  _ListParser(this._parsers);
  +  ListParser(this._parsers);
   
     @override
     List<Parser> get children => _parsers;
  
positive.code: /**
   * A parser that uses the first parser that succeeds.
   */
  class _ChoiceParser extends _ListParser {
  
    _ChoiceParser(parsers) : super(parsers);
  
  
negative.code: /**
   * A parser that parses a sequence of parsers.
   */
  class _SequenceParser extends ListParser {
  
    _SequenceParser(parsers) : super(parsers);
  
  