/*
Let's assume 3 person objects with an attribute age.
The first one is 10 years old,
the second one is 5 years old,
the third one is 40 years old.
*/
Project.sum('age').then(sum => {
// this will return 55
})
Project.sum('age', { where: { age: { [Op.gt]: 5 } } }).then(sum => {
// will be 50
})