Function immutable

immutable<V>(
options?: QueueOpts<V>,
...startingItems: readonly V[],
): IQueueImmutable<V>
Returns an immutable queue. Queues are useful if you want to treat 'older' or 'newer' items differently. Enqueing adds items at the back of the queue, while dequeing removes items from the front (ie. the oldest).
```
import { Queues } from "https://unpkg.com/ixfx/dist/collections.js"
let q = Queues.immutable();           // Create
q = q.enqueue(`a`, `b`);   // Add two strings
const front = q.peek();    // `a` is at the front of queue (oldest)
q = q.dequeue();           // q now just consists of `b`
```
Type Parameters
- V
  Type of values stored
Parameters
- options: QueueOpts<V> = {}
- ...startingItems: readonly V[]
  Index 0 is the front of the queue
Returns IQueueImmutable<V>
A new queue
Example: Cap size to 5 items, throwing away newest items already in queue.
```
const q = Queues.immutable({capacity: 5, discardPolicy: `newer`});
```