Function immutable

immutable<V>(
options?: StackOpts,
...startingItems: readonly V[],
): IStackImmutable<V>
Returns a stack. Immutable. Use Stacks.mutable for a mutable alternative.

The basic usage is push/pop to add/remove, returning the modified stack. Use the property peek to see what's on top.
Type Parameters
- V
Parameters
- options: StackOpts = {}
  Options
- ...startingItems: readonly V[]
  List of items to add to stack. Items will be pushed 'left to right', ie array index 0 will be bottom of the stack.
Returns IStackImmutable<V>
Example: Basic usage
```
// Create
let s = stack();
// Add one or more items
s = s.push(1, 2, 3, 4);
// See what's at the top of the stack
s.peek;      // 4

// Remove from the top of the stack, returning
// a new stack without item
s = s.pop();
s.peek;        // 3
```