public function register() {
		$tokens                   = parent::register();
		$tokens[ \T_BOOLEAN_NOT ] = \T_BOOLEAN_NOT;
		$tokens[ \T_INSTANCEOF ]  = \T_INSTANCEOF;
		$logical_operators        = Tokens::$booleanOperators;

		// Using array union to auto-dedup.
		return $tokens + $logical_operators;
	}