anchor.diff:  
     @override
     String toString() {
  -    if (_parent == null) return indent.toString();
  +    if (parent == null) return indent.toString();
       return '$parent:$indent';
     }
   }
  
positive.code:   int get totalUsedIndent => _totalUsedIndent!;
    int? _totalUsedIndent;
  
    bool get isNested => _parent != null;
  
    NestingLevel()
        : _parent = null,
          indent = 0;
  
    NestingLevel._(this._parent, this.indent);
  
    /// Creates a new deeper level of nesting indented [spaces] more characters
    /// that the outer level.
  
negative.code:   /// Clears the previously calculated total indent of this nesting level.
    void clearTotalUsedIndent() {
      _totalUsedIndent = null;
      parent?.clearTotalUsedIndent();
    }
  
    /// Calculates the total amount of indentation from this nesting level and
  