anchor.diff:  
     /// Parses an integer scalar.
     _ScalarNode parseInt(String content) {
  -    var match = new RegExp("^[-+]?[0-9]+\$").firstMatch(content);
  +    var match = new RegExp(r"^[-+]?[0-9]+$").firstMatch(content);
       if (match != null) {
         return new _ScalarNode(_Tag.yaml("int"),
             value: int.parse(match.group(0)));
       }
   
  -    match = new RegExp("^0o([0-7]+)\$").firstMatch(content);
  +    match = new RegExp(r"^0o([0-7]+)$").firstMatch(content);
       if (match != null) {
         int n = int.parse(match.group(1), radix: 8);
         return new _ScalarNode(_Tag.yaml("int"), value: n);
       }
   
  -    match = new RegExp("^0x[0-9a-fA-F]+\$").firstMatch(content);
  +    match = new RegExp(r"^0x[0-9a-fA-F]+$").firstMatch(content);
       if (match != null) {
         return new _ScalarNode(_Tag.yaml("int"),
             value: int.parse(match.group(0)));
  
positive.code:   /// Parses a floating-point scalar.
    _ScalarNode parseFloat(String content) {
      var match = new RegExp(
          "^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?\$").
        firstMatch(content);
      if (match != null) {
        // YAML allows floats of the form "0.", but Dart does not. Fix up those
  
negative.code: 
    /// Parses a null scalar.
    _ScalarNode parseNull(String content) {
      if (!new RegExp(r"^(null|Null|NULL|~|)$").hasMatch(content)) return null;
      return new _ScalarNode(_Tag.yaml("null"), value: null);
    }
  
    /// Parses a boolean scalar.
    _ScalarNode parseBool(String content) {
      var match = new RegExp(r"^(?:(true|True|TRUE)|(false|False|FALSE))$").
        firstMatch(content);
      if (match == null) return null;
      return new _ScalarNode(_Tag.yaml("bool"), value: match.group(1) != null);
  