strip file extension in Vala

string strip_file_extension (string filename, string extension) {
//written by Sergey "Shnatsel" Davidoff
//usage: strip_file_extension ("/path/to/file.extension", ".extension")
    var index_of_last_dot = filename.last_index_of (".");
    if (filename.slice (index_of_last_dot, filename.length) == extension) {
        return filename.slice (0, index_of_last_dot);
    } else {
        return filename;
    }
}