https://dev.to/_gdelgado/type-constraints-in-typescript-34ek
A type constraint is a "rule" that narrows down the possibilities of what a generic type could be.
We can thus narrow the possibilities of the generic type T to allow allow JSON values as follow:
const send = <T extends JSONValues>(data: T): Promise<null> => {
// ...
}
The only difference is that now we've appended extends JSONValues to the type variable declaration for T.
In plain english T extends JSONValues translates to, "T is a generic type that must conform to the definition of JSONValues".
