typescript add parameter to function definition

type FetchSecure = (
  ...args: [...[keycloak: KeycloakInstance], ...Parameters<typeof fetch>]
) => ReturnType<typeof fetch>;


For example, this takes the parameters from the http fetch api and assigns them to my new type with my response type override:

```
type Fetch = (...args: [...Parameters<typeof fetch>]) => Promise<any>;
// result: (input: RequestInfo | URL, init?: RequestInit | undefined) => Promise<any>
```

And then I can add my own parameters, like so:

```
type FetchHandler = (...args: [...Parameters<Fetch>, ...[anon?: boolean]]) => ReturnType<Fetch>
// results: (input: RequestInfo | URL, init?: RequestInit | undefined, anon?: boolean | undefined) => ReturnType<Fetch>
```

If we want get the individual function parameters we can do:

```
type InputParam = Parameters<Fetch>[0];
type InitParam = Parameters<Fetch>[1];
```