C# problem

Module Module1

    Sub Main()

        public void SetAllFilesAsReadOnly(string rootPath)
    {
        foreach (string file in Directory.EnumerateFiles(rootPath, "*.*", SearchOption.AllDirectories))
        {
            var attr = File.GetAttributes(file);
            // set read-only
            attr = attr | FileAttributes.ReadOnly;
            File.SetAttributes(file,attr);
        }
    }

    End Sub

End Module