anchor.diff:        return;
       }
   
  -    bool checkIfParameterIsNull(AstNode node) =>
  -        _isParameterWithQuestion(node, parameter) ||
  -        (node is BinaryExpression &&
  -            (_isParameterWithQuestionQuestion(node, parameter) ||
  -                _isComparingParameterWithNull(node, parameter)));
  -
  -    node.body
  -        .traverseNodesInDFS()
  -        .where(checkIfParameterIsNull)
  -        .forEach(rule.reportLint);
  +    node.body.accept(_BodyVisitor(parameter, rule));
     }
   }
  
positive.code:     var visitor =
          _Visitor(this, nnbdEnabled: context.isEnabled(Feature.non_nullable));
      registry.addMethodDeclaration(this, visitor);
    }
  }
  
  
negative.code: bool _isParameter(Expression expression, Element? parameter) =>
      expression.canonicalElement == parameter;
  
  bool _isParameterWithQuestionQuestion(
          BinaryExpression node, Element? parameter) =>
      node.operator.type == TokenType.QUESTION_QUESTION &&
  