after.cs

    public override bool Match(ITreeNode element, IMatchingContext context)
    {
      if (element == null)
        return false;

      if (element is ICSharpArgument arg)
        element = arg.Value;

      if (element is IExpressionInitializer exprInitializer)
        element = exprInitializer.Value;

      if (element is IAnonymousMemberDeclaration declaration)
      {
        if (!declaration.IsProjectionInitializer) return false;
        element = declaration.Expression;
      }

      if (element is ILambdaParameterDeclaration lambda)
        element = lambda.NameIdentifier;

      if (element is IFieldDeclaration fieldDecl)
        element = fieldDecl.NameIdentifier;

      if (element is IEventDeclaration eventDecl)
        element = eventDecl.NameIdentifier;

      if (element is IQueryRangeVariableDeclaration rangeVar)
        element = rangeVar.NameIdentifier;

      if (element is ICatchVariableDeclaration catchVar)
        element = catchVar.NameIdentifier;
      
      ...
    }

before.cs

    public override bool Match(ITreeNode element, IMatchingContext context)
    {
      if (element == null)
        return false;

      if (element is ICSharpArgument)
        element = ((ICSharpArgument)element).Value;

      if (element is IExpressionInitializer)
        element = ((IExpressionInitializer)element).Value;

      if (element is IAnonymousMemberDeclaration)
      {
        var declaration = (IAnonymousMemberDeclaration)element;
        if (!declaration.IsProjectionInitializer) return false;
        element = declaration.Expression;
      }

      if (element is ILambdaParameterDeclaration)
        element = ((ILambdaParameterDeclaration) element).NameIdentifier;

      if (element is IFieldDeclaration)
        element = ((IFieldDeclaration) element).NameIdentifier;

      if (element is IEventDeclaration)
        element = ((IEventDeclaration) element).NameIdentifier;

      if (element is IQueryRangeVariableDeclaration)
        element = ((IQueryRangeVariableDeclaration) element).NameIdentifier;

      if (element is ICatchVariableDeclaration)
        element = ((ICatchVariableDeclaration) element).NameIdentifier;
      
      ...
    }