Zend\Diactoros\Stream::isWritable PHP Method

    public function isWritable()
    {
        if (!$this->resource) {
            return false;
        }
        $meta = stream_get_meta_data($this->resource);
        $mode = $meta['mode'];
        return strstr($mode, 'x') || strstr($mode, 'w') || strstr($mode, 'c') || strstr($mode, 'a') || strstr($mode, '+');
    }