protected function sectionLedBy( string$leader, bool$allowSpace=false ):string
	{
		return $this->line->pregGet(...[
			(
				'/ '.preg_quote($leader)
				.
				($allowSpace?
					'((?!\()(?:[^ ]| (?=[a-zA-Z0-9]))+'
					:
					'([^ ]+'
				)
				.
				'|(?<exp>\((?:[^()]+|(?&exp)?)+?\)))(?= |$)/'
			),
			1,
		]);
	}