trait DuckLike {
  fn quack(&self);

  fn walk(&self) {
    println!("walking");
  }
}

struct Duck;

impl DuckLike for Duck {
  fn quack(&self) {
    println!("quack");
  }
}

struct Tsuchinoko;

impl DuckLike for Tsuchinoko {
  fn quack(&self) {
    println!("mew");
  }

  fn walk(&self) {
    println!("wriggling");
  }
}

impl DuckLike for i64 {
  fn quack(&self) {
    for _ in 0..*self {
      println!("quack");
    }
  }
}

fn main() {
  let duck = Duck;
  let tsuchinoko  = Tsuchinoko;
  let i = 3;
  duck.quack();
  tsuchinoko.quack();
  i.quack();
}