protected function doRead(int $offset, int $count): string
    {
        /** @var string|false $data */
        $data = substr($this->content, $offset, $count);
        return (false === $data) ? '' : $data;
    }
protected function doRead(int $offset, int $count): string
    {
        /** @var string|false $data */
        $data = substr($this->content, $offset, $count);
        return (false === $data) ? '' : $data;
    }
protected function doRead ( int $ offset , int $ count ) : string { /** @var string|false $data */ $ data = substr ( $ this -> content , $ offset , $ count ) ; return ( false === $ data ) ? '' : $ data ; }
actual reading of length starting at given offset

@param   int  $offset
@param   int  $count
@return  string
actual reading of length starting at given offset