将对象插入数据库时​​出错

Question

在mongodb中将对象插入数据库时​​，它会给出错误ReferenceError: WriteResult is not defined

> use school
switched to db school
> student = { "name":"binit", "age": 24, "subjects": ["math", "science", "litrature"] }
{
    "name" : "binit",
    "age" : 24,
    "subjects" : [
        "math",
        "science",
        "litrature"
    ]
}
> db.school.insert(student)
> WriteResult({ "nInserted" : 1 })
Fri Jul 17 15:49:17.038 ReferenceError: WriteResult is not defined