Read on Twitter
TypeScript experts: how do you normally patch a type that is missing something you need? I have a few examples in the codebase I'm working on, and I just keep adding ts-ignore's until I can get around to them 
Example: types/express-session adds a Session interface for req.session. However, it's not indexed by string so `req.session["key"]` is an error. I tried:
namespace express {
export interface Request {
session: { [k: string]: string }
}
}
but that overwrites it entirely
namespace express {
export interface Request {
session: { [k: string]: string }
}
}
but that overwrites it entirely
... so I don't get all the type information that was included in types/express-session in the first place. Ideally, what I'd like to do is just add a string index to the Session type.
