Advanced Node - "ops property of doc" - Registration of Users Lesson

Hi campers,

I’m back to Node after a hiatus. Going through the quality assurance lessons again, I found something on the lesson “Registration of New Users” that I don’t understand:
https://www.freecodecamp.org/learn/quality-assurance/advanced-node-and-express/registration-of-new-users

What does it mean that the “inserted document is held within the ops property of the doc”? What is the ops property? Is there a link to a MongoDB documentation that properly explains how the document in stored? (NOT using Mongoose)

doc.ops[0]

app.route('/register')
  .post((req, res, next) => {
    myDataBase.findOne({ username: req.body.username }, function(err, user) {
      if (err) {
        next(err);
      } else if (user) {
        res.redirect('/');
      } else {
        myDataBase.insertOne({
          username: req.body.username,
          password: req.body.password
        },
          (err, doc) => {
            if (err) {
              res.redirect('/');
            } else {
              // The inserted document is held within
              // the ops property of the doc
              next(null, doc.ops[0]);
            }
          }
        )
      }
    })
  },
    passport.authenticate('local', { failureRedirect: '/' }),
    (req, res, next) => {
      res.redirect('/profile');
    }
  );

Hey there,

More information is in the docs: insertOneWriteOpResult

To get there, follow the tree:

Hope this helps