anchor.diff:          span: _scanner.spanFrom(start));
     }
   
  +  List<Statement> _declarationChildren() => _children(() {
  +    if (_scanner.peekChar() == $at) return _declarationAtRule();
  +    return _declaration();
  +  });
  +
     /// Consumes whitespace if available and returns any comments it contained.
     List<Comment> _comments() {
       var nodes = <Comment>[];
  
positive.code: 
        nodes.add(comment);
      }
    }
  
    // ## Expressions
  
negative.code:         span: _scanner.spanFrom(start));
    }
  
    Declaration _declaration() {
      var start = _scanner.state;
      var name = _interpolatedIdentifier();
  