++mod_opt_type(dbs) ->
++ fun (A) -> A end;
++mod_opt_type(vhosts) ->
++ fun (A) -> A end;
++mod_opt_type(poll_users_settings) ->
++ fun (I) when is_integer(I), I > 0 -> I end;
++mod_opt_type(dolog_default) ->
++ fun (A) when is_boolean(A) -> A end;
++mod_opt_type(drop_messages_on_user_removal) ->
++ fun (A) when is_boolean(A) -> A end;
++mod_opt_type(ignore_jids) ->
++ fun (A) -> A end;
++mod_opt_type(groupchat) ->
++ fun (A) -> A end;
++mod_opt_type(purge_older_days) ->
++ fun (I) when is_integer(I), I > 0 -> I end;
++mod_opt_type(_) -> [dbs, vhosts, poll_users_settings, dolog_default, drop_messages_on_user_removal, ignore_jids, groupchat, purge_older_days].