Animal with flow types

script3.jsx

  function Animal(name: string, speed: number, focus: number) {
    this.name = name;
    this.speed = speed || 1;
    this.focus = focus || 1;
    this.position = 0;
    this.run = function() {
      if (Math.random() * 10 < this.focus) {
        this.position = this.position + this.speed;
      }
    };
  }