with_index

        # Enumerator::Lazy.with_index

(from ruby core)
### Implementation from Lazy
---
    lazy.with_index(offset = 0) {|(*args), idx| block }
    lazy.with_index(offset = 0)

---

If a block is given, returns a lazy enumerator that will iterate over
the given block for each element with an index, which starts from
`offset`, and returns a lazy enumerator that yields the same values
(without the index).

If a block is not given, returns a new lazy enumerator that includes the
index, starting from `offset`.

`offset`
:   the starting index to use


See Enumerator#with_index.