Creates an Iterator that is Peekable.

Examples

import { I } from "./mod.ts";

const iter = I.peekable(I.iter([1, 2, 3]));

console.log(iter.next()); // 1
console.log(iter.peek()); // 2
console.log(iter.next()); // 2
console.log(iter.next()); // 3
console.log(iter.peek()); // undefined
console.log(iter.next()); // undefined