protected function getChunk($offset)
	{
		if ( ! is_numeric($offset) || ! is_int(+$offset) || $offset < 0) {
			throw new \InvalidArgumentException(
				__METHOD__."() expects parameter one, offset, to be a positive "
					. "integer or zero"
			);	
		}
		
		$chunk = false;
		
		$text = (string) $this->text;
		
		if ($offset < mb_strlen($text)) {
			$chunk = mb_substr($text, $offset, $this->size, $this->encoding);
		} 
		
		return $chunk;
	}