I saw that the command to terminate the server is `:terminate` but this is not a valid command. ```julia function isvalidcmd(cmd) isempty(cmd) && return false Base.is_id_start_char(cmd[1]) || return false for c in cmd Base.is_id_char(c) || return false end true end ``` because this function returns false ```julia Base.is_id_start_char(':') ``` is there another way?