public function logicalAnd(self $other){
		
		$l = \max(array($this->count(), $other->count()));
		$new = new static();
		
		for($i = 0; $i < $l; ++$i){
			$new[$i] = isset($this[$i], $other[$i])
					? ($this[$i] && $other[$i])
					: false;
		}
		
		return $new;
		
	}