Zend\Diactoros\Stream::seek PHP Method

    public function seek($offset, $whence = SEEK_SET)
    {
        if (!$this->resource) {
            throw new RuntimeException('No resource available; cannot seek position');
        }
        if (!$this->isSeekable()) {
            throw new RuntimeException('Stream is not seekable');
        }
        $result = fseek($this->resource, $offset, $whence);
        if (0 !== $result) {
            throw new RuntimeException('Error seeking within stream');
        }
        return true;
    }