pharext\Cli\Command::warn PHP Method

    public function warn($fmt)
    {
        if (!$this->args->quiet) {
            if (!isset($fmt)) {
                $fmt = "%s\n";
                $arg = error_get_last()["message"];
            } else {
                $arg = array_slice(func_get_args(), 1);
            }
            vfprintf(STDERR, "Warning: {$fmt}", $arg);
        }
    }