private IEnumerator CheckChallenge()
    {
        //Check if any incoming challenge is received
        string url = "http://127.0.0.1:5000/challenges/?to_student_id=" + PlayerPrefs.GetString("userID");

        using (UnityWebRequest webRequest = UnityWebRequest.Get(url))
        {
            yield return(webRequest.SendWebRequest());

            ChallengerList challenges = JsonUtility.FromJson <ChallengerList>("{\"users\":" + webRequest.downloadHandler.text + "}");
            processChallenges(challenges);
        }
    }
    private void processChallenges(ChallengerList challenges)
    {
        //Process any challenges that are received
        int i = 0;

        Button[]   challengers     = new Button[3];
        TMP_Text[] challengersText = new TMP_Text[3];
        eventMenu.SetActive(true);
        challengerButton1.SetActive(true);
        challengerButton2.SetActive(true);
        challengerButton3.SetActive(true);
        challengers[0] = challengerButton1.GetComponent <Button>();
        challengers[1] = challengerButton2.GetComponent <Button>();
        challengers[2] = challengerButton3.GetComponent <Button>();
        for (i = 0; i < 3; i++)
        {
            challengersText[i] = challengers[i].GetComponentInChildren <TMP_Text>();
        }
        i = 0;
        foreach (ChallengerDetails challenge in challenges.users)
        {
            if (!challenge.is_completed)
            {
                if (i == 3)
                {
                    break;
                }
                challengersText[i].text = "You received a challenge from " + challenge.from_person_name;
                challengers[i].GetComponent <Challenger>().challengerID = challenge.from_student_id;
                challengers[i].GetComponent <Challenger>().quizID       = challenge.quiz_id;
                i++;
            }
        }
        if (i == 0)
        {
            eventMenu.SetActive(false);
        }
        else if (i < 3)
        {
            for (int j = 2; j > i - 1; j--)
            {
                GameObject button = GameObject.Find(string.Format("Challenger{0}", j));
                button.SetActive(false);
            }
        }
        if (i > 0)
        {
            notification.Play();
        }
    }