Four is alive
A four-empty-point space — whether straight four, bent four, or square four — is ALIVE regardless of who plays first. The defender can always split it into two eyes no matter where the attacker plays; the attacker cannot stop it. So if your enclosed space is at least four points in one of these shapes, your group is safe — you needn't spend a move defending it. Securing such a shape is a common endgame goal.