code: function insertOne(coll, doc, options, callback) {
    if (Array.isArray(doc)) {
      return callback(
        MongoError.create({ message: 'doc parameter must be an object', driver: true })
      );
    }
  
    insertDocuments(coll, [doc], options, (err, r) => {
      if (callback == null) return;
      if (err && callback) return callback(err);
      // Workaround for pre 2.6 servers
      if (r == null) return callback(null, { result: { ok: 1 } });
      // Add values to top level to ensure crud spec compatibility
      r.insertedCount = r.result.n;
      r.insertedId = doc._id;
      if (callback) callback(null, r);
    });
  }
docs: Insert a single document into the collection. See Collection.prototype.insertOne for more information.
  
  @method
  @param {Collection} a Collection instance.
  @param {object} doc Document to insert.
  @param {object} [options] Optional settings. See Collection.prototype.insertOne for a list of options.
  @param {Collection~insertOneWriteOpCallback} [callback] The command result callback