[{
        "username": "u1",
        "password": "u1",
        "email": "u1"
    },
    {
        "username": "u2",
        "password": "u2",
        "email": "u2"
    },
    {
        "username": "u3",
        "password": "u3",
        "email": "u3"
    }
]