Peekable iterator that allows to peek the next N
elements without consuming them.
Basic usage:
```rust let xs = [1, 2, 3, 4, 5, 6, 7, 8, 9]; // create an iterator that allows us to peek at the next 4 element let mut iter = xs.iter().peekable_n::<4>();
// peek() lets us see into the future asserteq!(iter.peek::<1>(), Some(&&1)); asserteq!(iter.peek::<3>(), Some(&&3));
// the iterator will not advance until we call next
asserteq!(iter.next(), Some(&1));
asserteq!(iter.next(), Some(&2));
```