let attr_list_of_tr_id_opt (doc_settings : t_doc_settings) (path : t_path) (classes : string list) (id_opt : tr_id option) : (string*string) list = match id_opt with | None -> [("class"), String.concat " " classes] | Some id -> List.concat [attr_list_of_ts_tag classes id.fld_id_tag;attr_list_of_tr_id doc_settings path id]