src/Leevel/Session/Session.php
protected function parseMicrotime(): string
    {
        list($usec, $sec) = explode(' ', microtime());

        return (string) ((float) $usec + (float) $sec);
    }
protected function parseMicrotime(): string
    {
        list($usec, $sec) = explode(' ', microtime());

        return (string) ((float) $usec + (float) $sec);
    }
生成微秒数.

@return string