Rectangle Area with Optional Height

Optional properties can drive different behaviors. If height is provided, compute width * height; otherwise treat the value as a square and compute width * width.

Your Task

• Complete the function area(rect: { width: number; height?: number }): number.
• If height exists, return rect.width * rect.height.
• Otherwise, return rect.width * rect.width.

Examples

• area({ width: 3 }) → 9
• area({ width: 3, height: 4 }) → 12