{
    "_id" : ObjectId("55819929579ddfe695d1a9d1"),
    "etestId" : ObjectId("557081b7840f2d4c5e55d416"),
    "questions" : [
        {
            "question_number" : 0,
            "question_type" : 1,
            "question" : "3+5?",
            "question_img" : "path/to/image",
            "answer_options" : [
                "10",
                "can be also a path/to/img",
                "8"
            ],
            "correct_answer" : [
                "0"
            ]
        },
        {
            "question_number" : 1,
            "question_type" : 0,
            "question" : "x+y=1?",
            "question_img" : "path/to/image",
            "answer_options" : [
                "x=1 y=0",
                "x=2 y=-1",
                "none of them"
            ],
            "correct_answer" : [
                "0",
                "1"
            ]
        },
        {
            "question_number" : 2,
            "question_type" : 2,
            "question" : "yo?",
            "question_img" : "path/to/image",
            "correct_answer" : [
                "yo"
            ]
        }
    ]
}