File: sample.rs
  struct Rectangle {
      width: u32,
      height: u32,
  }
  
_ fn main() {
      let rect1 = Rectangle { width: 30, height: 50 };
  
      println!(
~         "The perimeter of the rectangle is {} pixels.",
~         perimeter(&rect1)
      );
  }
  
  fn area(rectangle: &Rectangle) -> u32 {
      rectangle.width * rectangle.height
  }
+ 
+ fn perimeter(rectangle: &Rectangle) -> u32 {
+     (rectangle.width + rectangle.height) * 2
+ }