I am creating a custom js library/framework and I am currently researching the topic of custom variable creators. My goal is to create a new variable constructor called sync, which behaves like let, so basically these two would behave exactly the same from a typescript point of view.

sync test = true
let test = true

Any ideas on how I can add the keyword or simulate to vscode that sync is the same as let? Or any ideas on where I can look for resources so I get some guidance