function isSeekable()
    {
        $this->assertMetaData();
        
        if ($this->getMetaKey('wrapper_type')) {
            // This is a wrapper resource; challenge seekable ...
            if (false === $pos = ftell($this->rHandler))
                throw new \RuntimeException('Unable to determine stream position');

            try {
                // TODO Stream Reach EOF When Seek On it Sometimes!!
                if (-1 === @fseek($this->rHandler, $pos, SEEK_SET))
                    return false;
            } catch (\Exception $e) {
                // Maybe Fallback into wrapper handler for seek
                return false;
            }
        }
        
        return (bool) $this->getMetaKey('seekable');
    }