I have read the document for a long time, and I have a general understanding of the concept grammar and so on, but when I really write it, I still have a lot of problems and always get stuck.

such as the following

this.ctx.model.Role.remove({ _id: { $in: values } })

remove, but what are the possibilities of these keywords? In other words, where can I see all possible keywords similar to this $in?

this question seems to extend the hand of the party a little bit, asking for a light spray, because I really can"t find it. kiss me babe.