anchor.diff:  
     /// Parses a null scalar.
     _ScalarNode parseNull(String content) {
  -    if (!new RegExp("^(null|Null|NULL|~|)\$").hasMatch(content)) return null;
  +    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("^(?:(true|True|TRUE)|(false|False|FALSE))\$").
  +    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);
  
positive.code:           value: double.parse(matchStr));
      }
  
      match = new RegExp("^([+-]?)\.(inf|Inf|INF)\$").firstMatch(content);
      if (match != null) {
        var value = match.group(1) == "-" ? -double.INFINITY : double.INFINITY;
        return new _ScalarNode(_Tag.yaml("float"), value: value);
      }
  
      match = new RegExp("^\.(nan|NaN|NAN)\$").firstMatch(content);
      if (match != null) {
        return new _ScalarNode(_Tag.yaml("float"), value: double.NAN);
      }
  
negative.code:   /// Parses a floating-point scalar.
    _ScalarNode parseFloat(String content) {
      var match = new RegExp(
          r"^[-+]?(\.[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
  