protected function _setPart(array $contents, $part)
    {
        if (property_exists($this, $part)) {
            $this->{$part} = $this->_getSetOfLines($contents);
            $this->_parseTableSizes(true);
        } elseif (!in_array($part, self::$_table_parts)) {
            throw new InvalidArgumentException(
                sprintf('Unknown table part "%s"!', $part)
            );
        }
    }