if (!Physics.Bungee) {
  Physics.Bungee = function(config) {
    Physics.Constraint.call(this, config);
  };
  Physics.Bungee.prototype = Object.create(Physics.Constraint.prototype);
  Physics.Bungee.prototype.update = function() {
    var distance = Vector2.dist(this.one.pos, this.two.pos);
    if (distance > this.length) {
      this.springEffect();
    }
  };
}

if (!Physics.Bungee || KAPhy.version !== KAPhy.current) {
  Physics.Bungee = function(config) {
    Physics.Constraint.call(this, config);
  };
  Physics.Bungee.prototype = Object.create(Physics.Constraint.prototype);
  Physics.Bungee.prototype.update = function() {
    var distance = Vector2.dist(this.one.pos, this.two.pos);
    if (distance > this.length) {
      this.springEffect();
    }
  };
}

Update bungee.js