objectMongodb.js
function _delete(id, cb) {
    getCollection(function (err, collection) {
      if (err) { return cb(err); }
      collection.remove({
        _id: new ObjectID(id)
      }, cb);
    });
  }
function _delete(id, cb) {
    getCollection(function (err, collection) {
      if (err) { return cb(err); }
      collection.remove({
        _id: new ObjectID(id)
      }, cb);
    });
  }
[END update]