db.students.insertMany([
  { id: 1, name: 'Ryan', gender: 'M' },
  { id: 2, name: 'Joanna', gender: 'F', users:['a'] }
]);
db.students.updateOne({id:2},  { $set: {name:'sid'}, $push: { users: 89 } })
db.students.find({ gender: 'F' }); // shows 2nd record