this.go = function (currentState) {
    if (currentState == LightState.GREEN) {
      console.log("Green --> for 1 minute")
      this.change(LightState.YELLOW)
      return
      
    }
    if (currentState == LightState.YELLOW) {
      console.log("Yellow --> for 10 seconds")
      this.change(LightState.RED)
      return
    }
    if (currentState == LightState.RED) {
      console.log("Red --> for 1 minute");
      this.change(LightState.GREEN)
      return
    }
    if (currentState != LightState.GREEN && currentState != LightState.RED && currentState != LightState.YELLOW) {
      throw Error("Invalid State")
    }
}