Type Alias MountMap

MountMap: { [T in UpdateType]: Extract<Update, Record<T, object>> } & {
    [T in MessageSubType]: {
        message: ExtractPartial<
            Update.MessageUpdate["message"],
            Record<T, unknown>,
        >;
        update_id: number;
    }
}

Maps [[Composer.on]]'s updateType or messageSubType to a tt.Update subtype.