@@ -40,7 +40,9 @@ func (b *Budget) Charge(tokens int)Show 24 unchanged lines
4040 	if tokens < 0 {
4141 		return ErrNegativeCharge
4242 	}
43removed-	b.used += tokens
44removed-	return nil
43added+	if b.used+tokens > b.ceiling {
44added+		return fmt.Errorf("charge %d: %w", tokens, ErrBudgetReached)
45added+	}
46added+	b.used += tokens
4547 	return nil
4648 }