What is the type signature of the main exported function?

The main exported function getPort has the following type signature [index.d.ts:L66]:

export default function getPort(options?: Options): Promise<number>;

It accepts an optional Options object and returns a Promise that resolves to a number (the available port).

The Options type [index.d.ts:L3-L65] is an object that can include:

• port: a preferred port number or iterable of port numbers
• exclude: an iterable of port numbers to exclude from consideration
• reserve: a boolean (default false) to lock the port for the process lifetime
• host: a string specifying which host to check availability on
• Plus additional options inherited from Node's ListenOptions (except port)

FOLLOW_UPS:

• What does the reserve option actually do?
• How does getPort handle multiple preferred ports?
• What errors can getPort throw?